Primes whose sum of digits is 25
- Task
Show primes which sum of its decimal digits is 25
Find primes n such that n < 5000
- Stretch goal
Show the count of all such primes that do not contain any zeroes in the range:
- (997 ≤ n ≤ 1,111,111,111,111,111,111,111,111).
11l
F is_prime(a)
I a == 2
R 1B
I a < 2 | a % 2 == 0
R 0B
L(i) (3 .. Int(sqrt(a))).step(2)
I a % i == 0
R 0B
R 1B
F digit_sum(=n)
V result = 0
L n != 0
result += n % 10
n I/= 10
R result
V c = 0
L(n) 5000
I digit_sum(n) == 25 & is_prime(n)
c++
print(‘#4’.format(n), end' I c % 6 == 0 {"\n"} E ‘ ’)
print()
print(‘Found ’c‘ primes whose sum of digits is 25’)
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 Found 17 primes whose sum of digits is 25
Action!
INCLUDE "H6:SIEVE.ACT"
BYTE FUNC SumOfDigits(INT x)
BYTE s,d
s=0
WHILE x#0
DO
d=x MOD 10
s==+d
x==/10
OD
RETURN (s)
PROC Main()
DEFINE MAX="4999"
BYTE ARRAY primes(MAX+1)
INT i,count=[0]
Put(125) PutE() ;clear the screen
Sieve(primes,MAX+1)
FOR i=2 TO MAX
DO
IF primes(i)=1 AND SumOfDigits(i)=25 THEN
PrintI(i) Put(32)
count==+1
FI
OD
PrintF("%E%EThere are %I primes",count)
RETURN
- Output:
Screenshot from Atari 8-bit computer
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 There are 17 primes
Ada
-- Rosetta Code Task written in Ada
-- Primes whose sum of digits is 25
-- https://rosettacode.org/wiki/Primes_whose_sum_of_digits_is_25
-- November 2024, R. B. E.
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Primes_Whose_Sum_of_Digits_is_25 is
Max_Prime_Candidate : constant Positive := 5_000; -- per task description
function Is_Prime (N : in Natural) return Boolean is
Temp : Natural := 5;
begin
if N < 2 then
return False;
end if;
if N mod 2 = 0 then
return N = 2;
end if;
if N mod 3 = 0 then
return N = 3;
end if;
while Temp * Temp <= N loop
if N mod Temp = 0 then
return False;
end if;
Temp := Temp + 2;
if N mod Temp = 0 then
return False;
end if;
end loop;
return True;
end Is_Prime;
function Is_Sum_of_Digits_Equal_to_25 (N : Positive) return Boolean is
Local_N : Natural := N;
Sum : Natural := 0;
Current_Remainder : Natural;
begin
while Local_N > 0 loop
Current_Remainder := Local_N mod 10;
Sum := Sum + Current_Remainder;
Local_N := Local_N / 10;
end loop;
return Sum = 25;
end Is_Sum_of_Digits_Equal_to_25;
Prime_Count : Natural := 0;
begin
for I in 1..Max_Prime_Candidate loop
if Is_Sum_of_Digits_Equal_to_25 (I) then
if (Is_Prime (I)) then
Prime_Count := Prime_Count + 1;
Put (I, 0);
Put (" ");
end if;
end if;
end loop;
New_Line;
Put ("There are ");
Put (Prime_Count, 0);
Put (" primes less than ");
Put (Max_Prime_Candidate, 0);
Put_Line (" whose sum of digits is 25");
end Primes_Whose_Sum_of_Digits_is_25;
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 There are 17 primes less than 5000 whose sum of digits is 25
ALGOL 68
BEGIN # find primes whose digits sum to 25 #
# show all sum25 primes below 5000 #
PR read "primes.incl.a68" PR
[]BOOL prime = PRIMESIEVE 4999;
INT p25 count := 0;
FOR n TO UPB prime DO
IF prime[ n ] THEN
# have a prime, check for a sum25 prime #
INT digit sum := 0;
INT v := n;
WHILE v > 0 DO
INT digit = v MOD 10;
digit sum +:= digit;
v OVERAB 10
OD;
IF digit sum = 25 THEN
print( ( " ", whole( n, 0 ) ) );
p25 count +:= 1
FI
FI
OD;
print( ( newline, "Found ", whole( p25 count, 0 ), " sum25 primes below ", whole( UPB prime + 1, 0 ), newline ) )
END
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 Found 17 sum25 primes below 5000
Stretch Goal
Uses the candidate generating algorithm used by Phix, Go
Uses the Miller Rabin primality test and the pow mod procedure from prelude/pow_mod
BEGIN
PROC pow mod = (LONG LONG INT b,in e, modulus)LONG LONG INT: (
LONG LONG INT sq := b, e := in e;
LONG LONG INT out:= IF ODD e THEN b ELSE 1 FI;
e OVERAB 2;
WHILE e /= 0 DO
sq := sq * sq MOD modulus;
IF ODD e THEN out := out * sq MOD modulus FI ;
e OVERAB 2
OD;
out
);
INT p25 count := 0;
PROC sum25 = ( LONG LONG INT p, INT rem )VOID:
FOR i TO IF rem > 9 THEN 9 ELSE rem FI DO
IF rem > i THEN
sum25( ( p * 10 ) + i, rem - i )
ELIF ODD i AND i /= 5 THEN
LONG LONG INT n = ( p * 10 ) + i;
IF n MOD 3 /= 0 THEN
BOOL is prime := TRUE;
# miller rabin primality test #
INT k = 10;
LONG LONG INT d := n - 1;
INT s := 0;
WHILE NOT ODD d DO
d OVERAB 2;
s +:= 1
OD;
TO k WHILE is prime DO
LONG LONG INT a := 2 + ENTIER (random*(n-3));
LONG LONG INT x := pow mod(a, d, n);
IF x /= 1 THEN
BOOL done := FALSE;
TO s WHILE NOT done DO
IF x = n-1
THEN done := TRUE
ELSE x := x * x MOD n
FI
OD;
IF NOT done THEN IF x /= n-1 THEN is prime := FALSE FI FI
FI
OD;
# END miller rabin primality test #
IF is prime THEN
# IF ( p25 count + 1 ) MOD 100 = 0 THEN print( ( whole( p25 count + 1, -8 ), whole( n, -30 ), newline ) ) FI; #
p25 count +:= 1
FI
FI
FI
OD;
sum25( 0, 25 );
print( ( "There are ", whole( p25 count, 0 ), " sum25 primes that contain no zeroes", newline ) )
END
- Output:
Note that ALGOL 68G under Windows is fully interpreted so runtime is not of the same order as the Phix and Go samples. Under Linux with optimisation and compilation, it should be faster than under Windows.
There are 1525141 sum25 primes that contain no zeroes
ALGOL W
begin % find some primes whose digits sum to 25 %
% sets p( 1 :: n ) to a sieve of primes up to n %
procedure Eratosthenes ( logical array p( * ) ; integer value n ) ;
begin
p( 1 ) := false; p( 2 ) := true;
for i := 3 step 2 until n do p( i ) := true;
for i := 4 step 2 until n do p( i ) := false;
for i := 3 step 2 until truncate( sqrt( n ) ) do begin
integer ii; ii := i + i;
if p( i ) then for pr := i * i step ii until n do p( pr ) := false
end for_i ;
end Eratosthenes ;
integer MAX_NUMBER;
MAX_NUMBER := 4999;
begin
logical array prime( 1 :: MAX_NUMBER );
integer pCount;
% sieve the primes to MAX_NUMBER %
Eratosthenes( prime, MAX_NUMBER );
% find the primes whose digits sum to 25 %
pCount := 0;
for i := 1 until MAX_NUMBER do begin
if prime( i ) then begin
integer dSum, v;
v := i;
dSum := 0;
while v > 0 do begin
dSum := dSum + ( v rem 10 );
v := v div 10
end while_v_gt_0 ;
if dSum = 25 then begin
writeon( i_w := 4, s_w := 0, " ", i );
pCount := pCount + 1;
if pCount rem 20 = 0 then write()
end if_prime_pReversed
end if_prime_i
end for_i ;
write( i_w := 1, s_w := 0, "Found ", pCount, " sum25 primes below ", MAX_NUMBER + 1 )
end
end.
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 Found 17 sum25 primes below 5000
AppleScript
Functional
Not fast. This approach takes over 20 seconds here.
use AppleScript version "2.4"
use framework "Foundation"
use scripting additions
--------- PRIMES WITH DECIMAL DIGITS SUMMING TO 25 -------
-- primes :: [Int]
on primes()
-- A non-finite list of primes.
set ca to current application
script
property dict : ca's NSMutableDictionary's alloc's init()
property n : 2
on |λ|()
set xs to dict's objectForKey:(n as string)
repeat until missing value = xs
repeat with x in (xs as list)
set m to x as number
set k to (n + m) as string
set ys to (dict's objectForKey:(k))
if missing value ≠ ys then
set zs to ys
else
set zs to ca's NSMutableArray's alloc's init()
end if
(zs's addObject:(m))
(dict's setValue:(zs) forKey:(k))
(dict's removeObjectForKey:(n as string))
end repeat
set n to 1 + n
set xs to (dict's objectForKey:(n as string))
end repeat
set p to n
dict's setValue:({n}) forKey:((n * n) as string)
set n to 1 + n
set xs to missing value
return p
end |λ|
end script
end primes
-- digitSum :: Int -> Int
on digitSum(n)
-- Sum of the decimal digits of n.
set m to 0
set cs to characters of (n as string)
repeat with c in cs
set m to m + ((id of c) - 48)
end repeat
end digitSum
--------------------------- TEST -------------------------
on run
script q
on |λ|(x)
5000 > x
end |λ|
end script
script p
on |λ|(n)
25 = digitSum(n)
end |λ|
end script
set startTime to current date
set xs to takeWhile(q, filterGen(p, primes()))
set elapsedSeconds to ((current date) - startTime) as string
showList(xs)
end run
------------------------- GENERIC ------------------------
-- filterGen :: (a -> Bool) -> Gen [a] -> Gen [a]
on filterGen(p, gen)
-- Non-finite stream of values which are
-- drawn from gen, and satisfy p
script
property mp : mReturn(p)'s |λ|
on |λ|()
set v to gen's |λ|()
repeat until mp(v)
set v to gen's |λ|()
end repeat
return v
end |λ|
end script
end filterGen
-- intercalateS :: String -> [String] -> String
on intercalate(delim, xs)
set {dlm, my text item delimiters} to ¬
{my text item delimiters, delim}
set s to xs as text
set my text item delimiters to dlm
s
end intercalate
-- map :: (a -> b) -> [a] -> [b]
on map(f, xs)
-- The list obtained by applying f
-- to each element of xs.
tell mReturn(f)
set lng to length of xs
set lst to {}
repeat with i from 1 to lng
set end of lst to |λ|(item i of xs, i, xs)
end repeat
return lst
end tell
end map
-- mReturn :: First-class m => (a -> b) -> m (a -> b)
on mReturn(f)
-- 2nd class handler function lifted into 1st class script wrapper.
if script is class of f then
f
else
script
property |λ| : f
end script
end if
end mReturn
-- showList :: [a] -> String
on showList(xs)
"[" & intercalate(",", map(my str, xs)) & "]"
end showList
-- str :: a -> String
on str(x)
x as string
end str
-- takeWhile :: (a -> Bool) -> Gen [a] -> [a]
on takeWhile(p, xs)
set ys to {}
set v to |λ|() of xs
tell mReturn(p)
repeat while (its |λ|(v))
set end of ys to v
set v to xs's |λ|()
end repeat
end tell
return ys
end takeWhile
- Output:
[997,1699,1789,1879,1987,2689,2797,2887,3499,3697,3769,3877,3967,4597,4759,4957,4993]
Idiomatic
Primes with silly properties are getting a bit tedious. But hey. This takes just under 0.02 seconds.
on sieveOfEratosthenes(limit)
script o
property numberList : {missing value}
end script
repeat with n from 2 to limit
set end of o's numberList to n
end repeat
repeat with n from 2 to (limit ^ 0.5) div 1
if (item n of o's numberList is n) then
repeat with multiple from n * n to limit by n
set item multiple of o's numberList to missing value
end repeat
end if
end repeat
return o's numberList's numbers
end sieveOfEratosthenes
on sumOfDigits(n) -- n assumed to be a positive decimal integer.
set sum to n mod 10
set n to n div 10
repeat until (n = 0)
set sum to sum + n mod 10
set n to n div 10
end repeat
return sum
end sumOfDigits
on numbersWhoseDigitsSumTo(numList, targetSum)
script o
property numberList : numList
property output : {}
end script
repeat with n in o's numberList
if (sumOfDigits(n) = targetSum) then set end of o's output to n's contents
end repeat
return o's output
end numbersWhoseDigitsSumTo
-- Task code:
return numbersWhoseDigitsSumTo(sieveOfEratosthenes(4999), 25)
- Output:
{997, 1699, 1789, 1879, 1987, 2689, 2797, 2887, 3499, 3697, 3769, 3877, 3967, 4597, 4759, 4957, 4993}
Arturo
primes: select 1..5000 => prime?
loop split.every: 3 select primes 'p [25 = sum digits p] 'a ->
print map a => [pad to :string & 5]
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
AWK
# syntax: GAWK -f PRIMES_WHICH_SUM_OF_DIGITS_IS_25.AWK
BEGIN {
start = 1
stop = 5000
for (i=start; i<=stop; i++) {
if (is_prime(i)) {
sum = 0
for (j=1; j<=length(i); j++) {
sum += substr(i,j,1)
}
if (sum == 25) {
printf("%d ",i)
count++
}
}
}
printf("\nPrime numbers %d-%d whose digits sum to 25: %d\n",start,stop,count)
exit(0)
}
function is_prime(x, i) {
if (x <= 1) {
return(0)
}
for (i=2; i<=int(sqrt(x)); i++) {
if (x % i == 0) {
return(0)
}
}
return(1)
}
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 Prime numbers 1-5000 whose digits sum to 25: 17
BASIC
BASIC256
function isprime(num)
for i = 2 to int(sqr(num))
if (num mod i = 0) then return False
next i
return True
end function
function digit_sum(num)
sum25 = 0
for j = 1 to length(num)
sum25 += int(mid(string(num),j,1))
next j
return sum25
end function
inicio = 1: final = 5000
total = 0
for i = inicio to final
if isprime(i) and (digit_sum(i) = 25) then
total += 1
print i; " ";
end if
next i
print chr(13) + chr(13)
print "Se encontraron "; total; " primos sum25 por debajo de "; final
end
- Output:
Igual que la entrada de FreeBASIC.
C
#include <stdbool.h>
#include <stdio.h>
bool is_prime(int n) {
int i = 5;
if (n < 2) {
return false;
}
if (n % 2 == 0) {
return n == 2;
}
if (n % 3 == 0) {
return n == 3;
}
while (i * i <= n) {
if (n % i == 0) {
return false;
}
i += 2;
if (n % i == 0) {
return false;
}
i += 4;
}
return true;
}
int digit_sum(int n) {
int sum = 0;
while (n > 0) {
int rem = n % 10;
n /= 10;
sum += rem;
}
return sum;
}
int main() {
int n;
for (n = 2; n < 5000; n++) {
if (is_prime(n) && digit_sum(n) == 25) {
printf("%d ", n);
}
}
return 0;
}
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
C++
Stretch goal solved the same way as Phix and Go.
#include <algorithm>
#include <chrono>
#include <iomanip>
#include <iostream>
#include <string>
#include <gmpxx.h>
bool is_probably_prime(const mpz_class& n) {
return mpz_probab_prime_p(n.get_mpz_t(), 3) != 0;
}
bool is_prime(int n) {
if (n < 2)
return false;
if (n % 2 == 0)
return n == 2;
if (n % 3 == 0)
return n == 3;
for (int p = 5; p * p <= n; p += 4) {
if (n % p == 0)
return false;
p += 2;
if (n % p == 0)
return false;
}
return true;
}
int digit_sum(int n) {
int sum = 0;
for (; n > 0; n /= 10)
sum += n % 10;
return sum;
}
int count_all(const std::string& str, int rem) {
int count = 0;
if (rem == 0) {
switch (str.back()) {
case '1':
case '3':
case '7':
case '9':
if (is_probably_prime(mpz_class(str)))
++count;
break;
default:
break;
}
} else {
for (int i = 1; i <= std::min(9, rem); ++i)
count += count_all(str + char('0' + i), rem - i);
}
return count;
}
int main() {
std::cout.imbue(std::locale(""));
const int limit = 5000;
std::cout << "Primes < " << limit << " whose digits sum to 25:\n";
int count = 0;
for (int p = 1; p < limit; ++p) {
if (digit_sum(p) == 25 && is_prime(p)) {
++count;
std::cout << std::setw(6) << p << (count % 10 == 0 ? '\n' : ' ');
}
}
std::cout << '\n';
auto start = std::chrono::steady_clock::now();
count = count_all("", 25);
auto end = std::chrono::steady_clock::now();
std::cout << "\nThere are " << count
<< " primes whose digits sum to 25 and include no zeros.\n";
std::cout << "Time taken: "
<< std::chrono::duration<double>(end - start).count() << "s\n";
return 0;
}
- Output:
//https://tio.run/#cpp-gcc -lgmp -O3 Primes < 5,000 whose digits sum to 25: 997 1,699 1,789 1,879 1,987 2,689 2,797 2,887 3,499 3,697 3,769 3,877 3,967 4,597 4,759 4,957 4,993 There are 1,525,141 primes whose digits sum to 25 and include no zeros. Time taken: 10.6088s ..... Real time: 11.214 s User time: 11.075 s Sys. time: 0.082 s CPU share: 99.50 % Exit code: 0
D
import std.bigint;
import std.stdio;
bool isPrime(BigInt n) {
if (n < 2) {
return false;
}
if (n % 2 == 0) {
return n == 2;
}
if (n % 3 == 0) {
return n == 3;
}
auto i = BigInt(5);
while (i * i <= n) {
if (n % i == 0){
return false;
}
i += 2;
if (n % i == 0){
return false;
}
i += 4;
}
return true;
}
int digitSum(BigInt n) {
int result;
while (n > 0) {
result += n % 10;
n /= 10;
}
return result;
}
void main() {
for (auto n = BigInt(2); n < 5_000; n++) {
if (n.isPrime && n.digitSum == 25) {
write(n, ' ');
}
}
writeln;
}
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Delphi
program Primes_which_sum_of_digits_is_25;
{$APPTYPE CONSOLE}
uses
System.SysUtils,
PrimTrial;
var
row: Integer = 0;
limit1: Integer = 25;
limit2: Integer = 5000;
function Sum25(n: Integer): boolean;
var
sum: Integer;
str: string;
c: char;
begin
sum := 0;
str := n.ToString;
for c in str do
inc(sum, strToInt(c));
Result := sum = limit1;
end;
begin
for var n := 1 to limit2-1 do
begin
if isPrime(n) and sum25(n) then
begin
inc(row);
write(n: 4, ' ');
if (row mod 5) = 0 then
writeln;
end;
end;
readln;
end.
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
EasyLang
fastfunc isprim num .
i = 2
while i <= sqrt num
if num mod i = 0
return 0
.
i += 1
.
return 1
.
fastfunc nextprim prim .
repeat
prim += 1
until isprim prim = 1
.
return prim
.
func digok n .
while n > 0
dsum += n mod 10
n = n div 10
.
return if dsum = 25
.
p = 2
repeat
if digok p = 1
write p & " "
.
p = nextprim p
until p >= 5000
.
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
F#
// Primes to 5000 who's sum of digits is 25. Nigel Galloway: April 1st., 2021
let rec fN g=function n when n<10->n+g=25 |n->fN(g+n%10)(n/10)
primes32()|>Seq.takeWhile((>)5000)|>Seq.filter fN|>Seq.iter(printf "%d "); printfn ""
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Factor
USING: kernel lists lists.lazy math math.primes.lists prettyprint ;
: digit-sum ( n -- sum )
0 swap [ 10 /mod rot + swap ] until-zero ;
: lprimes25 ( -- list ) lprimes [ digit-sum 25 = ] lfilter ;
lprimes25 [ 5,000 < ] lwhile [ . ] leach
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Forth
: prime? ( n -- ? ) here + c@ 0= ;
: notprime! ( n -- ) here + 1 swap c! ;
: prime_sieve { n -- }
here n erase
0 notprime!
1 notprime!
n 4 > if
n 4 do i notprime! 2 +loop
then
3
begin
dup dup * n <
while
dup prime? if
n over dup * do
i notprime!
dup 2* +loop
then
2 +
repeat
drop ;
: digit_sum ( u -- u )
dup 10 < if exit then
10 /mod recurse + ;
: prime25? { p -- ? }
p prime? if
p digit_sum 25 =
else
false
then ;
: .prime25 { n -- }
." Primes < " n . ." whose digits sum to 25:" cr
n prime_sieve
0
n 0 do
i prime25? if
i 5 .r
1+ dup 10 mod 0= if cr then
then
loop
cr ." Count: " . cr ;
5000 .prime25
bye
- Output:
Primes < 5000 whose digits sum to 25: 997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 Count: 17
FreeBASIC
Function isprime(num As Ulongint) As Boolean
For i As Integer = 2 To Sqr(num)
If (num Mod i = 0) Then Return False
Next i
Return True
End Function
Function digit_sum(num As Integer) As Integer
Dim As Integer sum25 = 0
For j As Integer = 1 To Len(num)
sum25 += Val(Mid(Str(num),j,1))
Next j
Return sum25
End Function
Dim As Integer inicio = 1, final = 5000, total = 0
For i As Integer = inicio To final
If (isprime(i)) And (digit_sum(i) = 25) Then
total += 1
Print Using " ####"; i;
If (total Mod 9) = 0 Then Print
End If
Next i
Print !"\n\nSe encontraron"; total; " primos sum25 por debajo de"; finalSleep
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 Se encontraron 17 primos sum25 por debajo de 5000
Frink
println[select[primes[2,4999], {|x| sum[integerDigits[x]] == 25}]]
- Output:
[997, 1699, 1789, 1879, 1987, 2689, 2797, 2887, 3499, 3697, 3769, 3877, 3967, 4597, 4759, 4957, 4993]
Go
This uses the Phix routine for the stretch goal though I've had to plug in a GMP wrapper to better the Phix time. Using Go's native big.Int, the time was slightly slower than Phix at 1 minute 28 seconds.
package main
import (
"fmt"
big "github.com/ncw/gmp"
"time"
)
// for small numbers
func sieve(limit int) []bool {
limit++
// True denotes composite, false denotes prime.
c := make([]bool, limit) // all false by default
c[0] = true
c[1] = true
// no need to bother with even numbers over 2 for this task
p := 3 // Start from 3.
for {
p2 := p * p
if p2 >= limit {
break
}
for i := p2; i < limit; i += 2 * p {
c[i] = true
}
for {
p += 2
if !c[p] {
break
}
}
}
return c
}
func sumDigits(n int) int {
sum := 0
for n > 0 {
sum += n % 10
n /= 10
}
return sum
}
func min(a, b int) int {
if a < b {
return a
}
return b
}
// for big numbers
func countAll(p string, rem, res int) int {
if rem == 0 {
b := p[len(p)-1]
if b == '1' || b == '3' || b == '7' || b == '9' {
z := new(big.Int)
z.SetString(p, 10)
if z.ProbablyPrime(1) {
res++
}
}
} else {
for i := 1; i <= min(9, rem); i++ {
res = countAll(p+fmt.Sprintf("%d", i), rem-i, res)
}
}
return res
}
func commatize(n int) string {
s := fmt.Sprintf("%d", n)
if n < 0 {
s = s[1:]
}
le := len(s)
for i := le - 3; i >= 1; i -= 3 {
s = s[0:i] + "," + s[i:]
}
if n >= 0 {
return s
}
return "-" + s
}
func main() {
start := time.Now()
c := sieve(4999)
var primes25 []int
for i := 997; i < 5000; i += 2 {
if !c[i] && sumDigits(i) == 25 {
primes25 = append(primes25, i)
}
}
fmt.Println("The", len(primes25), "primes under 5,000 whose digits sum to 25 are:")
fmt.Println(primes25)
n := countAll("", 25, 0)
fmt.Println("\nThere are", commatize(n), "primes whose digits sum to 25 and include no zeros.")
fmt.Printf("\nTook %s\n", time.Since(start))
}
- Output:
The 17 primes under 5,000 whose digits sum to 25 are: [997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993] There are 1,525,141 primes whose digits sum to 25 and include no zeros. Took 25.300758564s
Haskell
import Data.Bifunctor (second)
import Data.List (replicate)
import Data.List.Split (chunksOf)
import Data.Numbers.Primes (primes)
--------- PRIMES WITH DECIMAL DIGITS SUMMING TO 25 -------
matchingPrimes :: [Int]
matchingPrimes =
takeWhile
(< 5000)
[n | n <- primes, 25 == decimalDigitSum n]
decimalDigitSum :: Int -> Int
decimalDigitSum n =
snd $
until
((0 ==) . fst)
(\(n, x) -> second (+ x) $ quotRem n 10)
(n, 0)
--------------------------- TEST -------------------------
main :: IO ()
main = do
let w = length (show (last matchingPrimes))
mapM_ putStrLn $
( show (length matchingPrimes)
<> " primes (< 5000) with decimal digits totalling 25:\n"
) :
( unwords
<$> chunksOf
4
(justifyRight w ' ' . show <$> matchingPrimes)
)
justifyRight :: Int -> Char -> String -> String
justifyRight n c = (drop . length) <*> (replicate n c <>)
- Output:
17 primes (< 5000) with decimal digits totalling 25: 997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
J
(#~ 25 = +/@("."0@":)"0) p: i. _1 p: 5000
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Java
import java.math.BigInteger;
public class PrimeSum {
private static int digitSum(BigInteger bi) {
int sum = 0;
while (bi.compareTo(BigInteger.ZERO) > 0) {
BigInteger[] dr = bi.divideAndRemainder(BigInteger.TEN);
sum += dr[1].intValue();
bi = dr[0];
}
return sum;
}
public static void main(String[] args) {
BigInteger fiveK = BigInteger.valueOf(5_000);
BigInteger bi = BigInteger.valueOf(2);
while (bi.compareTo(fiveK) < 0) {
if (digitSum(bi) == 25) {
System.out.print(bi);
System.out.print(" ");
}
bi = bi.nextProbablePrime();
}
System.out.println();
}
}
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
JavaScript
(() => {
"use strict";
// ---- PRIMES WITH DECIMAL DIGITS SUMMING TO 25 -----
// digitSum :: Int -> Int
const digitSum = n =>
`${n}`.split("").reduce(
(a, c) => a + (c.codePointAt(0) - 48),
0
);
// primes :: [Int]
const primes = function* () {
// Non finite sequence of prime numbers.
const dct = {};
let n = 2;
while (true) {
if (n in dct) {
dct[n].forEach(p => {
const np = n + p;
dct[np] = (dct[np] || []).concat(p);
delete dct[n];
});
} else {
yield n;
dct[n * n] = [n];
}
n = 1 + n;
}
};
// ---------------------- TEST -----------------------
// main :: IO ()
const main = () =>
unlines(
chunksOf(5)(
takeWhileGen(n => 5000 > n)(
filterGen(n => 25 === digitSum(n))(
primes()
)
).map(str)
).map(unwords)
);
// --------------------- GENERIC ---------------------
// chunksOf :: Int -> [a] -> [[a]]
const chunksOf = n => {
// xs split into sublists of length n.
// The last sublist will be short if n
// does not evenly divide the length of xs .
const go = xs => {
const chunk = xs.slice(0, n);
return 0 < chunk.length ? (
[chunk].concat(
go(xs.slice(n))
)
) : [];
};
return go;
};
// filterGen :: (a -> Bool) -> Gen [a] -> Gen [a]
const filterGen = p => xs => {
// Non-finite stream of values which are
// drawn from gen, and satisfy p
const go = function* () {
let x = xs.next();
while (!x.done) {
const v = x.value;
if (p(v)) {
yield v;
}
x = xs.next();
}
};
return go(xs);
};
// str :: a -> String
const str = x =>
x.toString();
// takeWhileGen :: (a -> Bool) -> Gen [a] -> [a]
const takeWhileGen = p =>
// Values drawn from xs until p matches.
xs => {
const ys = [];
let
nxt = xs.next(),
v = nxt.value;
while (!nxt.done && p(v)) {
ys.push(v);
nxt = xs.next();
v = nxt.value;
}
return ys;
};
// unlines :: [String] -> String
const unlines = xs =>
// A single string formed by the intercalation
// of a list of strings with the newline character.
xs.join("\n");
// unwords :: [String] -> String
const unwords = xs =>
// A space-separated string derived
// from a list of words.
xs.join(" ");
return main();
})();
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
jq
Works with jq
Works with gojq, the Go implementation of jq
The stretch goal is currently beyond the practical capabilities of both the C and Go-based implementations of jq, so only a simple solution to the primary task is shown here.
A suitable definition of `is_prime` may be found at Erdős-primes#jq and is therefore not repeated here.
Preliminaries
def digits: tostring | explode | map( [.]|implode|tonumber);
def emit_until(cond; stream): label $out | stream | if cond then break $out else . end;
The Task
# Output: primes whose decimal representation has no 0s and whose sum of digits is $sum > 2
def task($sum):
# Input: array of digits
def nozeros: select(all(.[]; . != 0));
range(3;infinite;2)
| select(digits | (.[-1] != 5 and nozeros and (add == $sum)) )
| select(is_prime);
emit_until(. >= 5000; task(25) )
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Julia
using Primes
let
pmask, pcount = primesmask(1, 5000), 0
issum25prime(n) = pmask[n] && sum(digits(n)) == 25
println("Primes with digits summing to 25 between 0 and 5000:")
for n in 1:4999
if issum25prime(n)
pcount += 1
print(rpad(n, 5))
end
end
println("\nTotal found: $pcount")
end
- Output:
Primes with digits summing to 25 between 0 and 5000: 997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 Total found: 17
Stretch goal
using Primes, Formatting
function sum25(p::String, rm, res)
if rm == 0
if p[end] in "1379" && isprime(parse(Int128, p))
res += 1
end
else
for i in 1:min(rm, 9)
res = sum25(p * string(i), rm - i, res)
end
end
return res
end
@time println("There are ", format(sum25("", 25, 0), commas=true),
" primes whose digits sum to 25 without any zero digits.")
- Output:
There are 1,525,141 primes whose digits sum to 25 without any zero digits. 29.377893 seconds (100.61 M allocations: 4.052 GiB, 0.55% gc time)
Kotlin
import java.math.BigInteger
fun digitSum(bi: BigInteger): Int {
var bi2 = bi
var sum = 0
while (bi2 > BigInteger.ZERO) {
val dr = bi2.divideAndRemainder(BigInteger.TEN)
sum += dr[1].toInt()
bi2 = dr[0]
}
return sum
}
fun main() {
val fiveK = BigInteger.valueOf(5_000)
var bi = BigInteger.valueOf(2)
while (bi < fiveK) {
if (digitSum(bi) == 25) {
print(bi)
print(" ")
}
bi = bi.nextProbablePrime()
}
println()
}
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Ksh
#!/bin/ksh
# Primes which sum of digits is 25
# # Variables:
#
integer MAXN=5000 SUM=25
# # Functions:
#
# # Function _sumdigits(n, sum) - return 1 if sum of n's digits = sum
#
function _sumdigits {
typeset _n ; integer _n=$1
typeset _sum ; integer _sum=$2
typeset _i _dsum ; integer _i _dsum=0
for ((_i=0; _i<${#_n}; _i++)); do
(( _dsum+=${_n:_i:1} ))
done
return $(( _dsum == _sum ))
}
# # Function _isprime(n) return 1 for prime, 0 for not prime
#
function _isprime {
typeset _n ; integer _n=$1
typeset _i ; integer _i
(( _n < 2 )) && return 0
for (( _i=2 ; _i*_i<=_n ; _i++ )); do
(( ! ( _n % _i ) )) && return 0
done
return 1
}
######
# main #
######
for ((i=3; i<$MAXN; i++)); do
_isprime ${i} || _sumdigits ${i} $SUM || printf "%d " ${i}
done
echo
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Mathematica /Wolfram Language
Select[Prime[Range@PrimePi[4999]], IntegerDigits /* Total /* EqualTo[25]]
- Output:
{997, 1699, 1789, 1879, 1987, 2689, 2797, 2887, 3499, 3697, 3769, 3877, 3967, 4597, 4759, 4957, 4993}
Nanoquery
// find primes using the sieve of eratosthenes
// https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes#Pseudocode
def find_primes(upper_bound)
a = {true} * (upper_bound + 1)
for i in range(2, int(sqrt(upper_bound)))
if a[i]
for j in range(i ^ 2, upper_bound, i)
a[j] = false
end for
end if
end for
primes = {}
for i in range(2, len(a) - 1)
if a[i]
primes.append(i)
end if
end for
return primes
end find_primes
def sum_digits(num)
digits = str(num)
digit_sum = 0
for i in range(0, len(digits) - 1)
digit_sum += int(digits[i])
end for
return digit_sum
end sum_digits
primes_to_check = find_primes(5000)
for prime in primes_to_check
if sum_digits(prime) = 25
print prime + " "
end if
end for
println
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Nim
Task
import strutils, sugar
func isPrime(n: Natural): bool =
if n < 2: return false
if n mod 2 == 0: return n == 2
if n mod 3 == 0: return n == 3
var d = 5
while d * d <= n:
if n mod d == 0: return false
inc d, 2
if n mod d == 0: return false
inc d, 4
result = true
func digitSum(n: Natural): int =
var n = n
while n != 0:
result += n mod 10
n = n div 10
let result = collect(newSeq):
for n in countup(3, 5000, 2):
if digitSum(n) == 25 and n.isPrime: n
for i, n in result:
stdout.write ($n).align(4), if (i + 1) mod 6 == 0: '\n' else: ' '
echo()
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Stretch goal
import std/monotimes, strformat, strutils
import bignum
func sum25(p: string; rm, res: Natural): Natural =
result = res
if rm == 0:
if p[^1] in "1379" and probablyPrime(newInt(p), 25) != 0:
inc result
else:
for i in 1..min(rm, 9):
result = sum25(p & chr(i + ord('0')), rm - i, result)
let t0 = getMonoTime()
let count = $sum25("", 25, 0)
echo &"There are {count.insertSep()} primes whose digits sum to 25 without any zero digits."
echo "\nExecution time: ", getMonoTime() - t0
- Output:
There are 1_525_141 primes whose digits sum to 25 without any zero digits. Execution time: (seconds: 12, nanosecond: 182051288)
Pascal
added only strechted goal.Generating the combination of the digits for the numbers and afterwards generating the Permutations with some identical elements
Now seting one digit out of 1,3,7,9 to the end and permute the rest of the digits in front.
So much less numbers have to be tested.10.5e6 instead of 16.4e6.Generating of the numbers is reduced in the same ratio.
program Perm5aus8;
//formerly roborally take 5 cards out of 8
{$IFDEF FPC}
{$mode Delphi}
{$Optimization ON,All}
{$ELSE}
{$APPTYPE CONSOLE}
{$ENDIF}
uses
sysutils,
gmp;
const
cTotalSum = 31;
cMaxCardsOnDeck = cTotalSum;//8
CMaxCardsUsed = cTotalSum;//5
type
tDeckIndex = 0..cMaxCardsOnDeck-1;
tSequenceIndex = 0..CMaxCardsUsed-1;
tDiffCardCount = 0..9;
tSetElem = record
Elem : tDiffCardCount;
Elemcount : tDeckIndex;
end;
tSet = record
RemSet : array [low(tDiffCardCount)..High(tDiffCardCount)] of tSetElem;
MaxUsedIdx,
TotElemCnt : byte;
end;
tRemainSet = array [low(tSequenceIndex)..High(tSequenceIndex)+1] of tSet;
tCardSequence = array [low(tSequenceIndex)..High(tSequenceIndex)] of tDiffCardCount;
var
ManifoldOfDigit : array[tDiffCardCount] of Byte;
TotalUsedDigits : array[tDeckIndex] of Byte;
RemainSets : tRemainSet;
CardString : AnsiString;
PrimeCount : integer;
PermCount : integer;
//*****************************************************************************
var
CS : pchar;
z : mpz_t;
procedure SetInit(var ioSet:tSet);
var
i : integer;
begin
with ioSet do
begin
MaxUsedIdx := 0;
For i := Low(tDiffCardCount) to High(tDiffCardCount) do
with RemSet[i] do
begin
ElemCount := 0;
Elem := 0;
end;
end;
end;
procedure CheckPrime;inline;
begin
mpz_set_str(z,CS,10);
inc(PrimeCount,ORD(mpz_probab_prime_p(z,3)>0));
end;
procedure Permute(depth,MaxCardsUsed:NativeInt);
var
pSetElem : ^tSetElem;
i : NativeInt;
begin
i := 0;
pSetElem := @RemainSets[depth].RemSet[i];
repeat
if pSetElem^.Elemcount <> 0 then begin
//take one of the same elements of the stack
//insert in result here string
CS[depth] := chr(pSetElem^.Elem+Ord('0'));
//done one permutation
IF depth = MaxCardsUsed then
begin
inc(permCount);
CheckPrime;
end
else
begin
dec(pSetElem^.ElemCount);
RemainSets[depth+1]:= RemainSets[depth];
Permute(depth+1,MaxCardsUsed);
//re-insert that element
inc(pSetElem^.ElemCount);
end;
end;
//move on to the next digit
inc(pSetElem);
inc(i);
until i >=RemainSets[depth].MaxUsedIdx;
end;
procedure Check(n:nativeInt);
var
i,dgtCnt,cnt,dgtIdx : NativeInt;
Begin
SetInit(RemainSets[0]);
dgtCnt := 0;
dgtIdx := 0;
//creating the start set.
with RemainSets[0] do
Begin
For i in tDiffCardCount do
Begin
cnt := ManifoldOfDigit[i];
if cnt > 0 then
Begin
with RemSet[dgtIdx] do
Begin
Elemcount := cnt;
Elem := i;
end;
inc(dgtCnt,cnt);
inc(dgtIdx);
end;
end;
TotElemCnt := dgtCnt;
MaxUsedIdx := dgtIdx;
CS := @CardString[1];
//Check only useful end-digits
For i := 0 to dgtIdx-1 do
Begin
if RemSet[i].Elem in[1,3,7,9]then
Begin
CS[dgtCnt-1] := chr(RemSet[i].Elem+Ord('0'));
CS[dgtCnt] := #00;
dec(RemSet[i].ElemCount);
permute(0,dgtCnt-2);
inc(RemSet[i].ElemCount);
end;
end;
end;
end;
procedure AppendToSum(n,dgt,remsum:NativeInt);
var
i: NativeInt;
begin
inc(ManifoldOfDigit[dgt]);
IF remsum > 0 then
For i := dgt to 9 do
AppendToSum(n+1,i,remsum-i)
else
Begin
if remsum = 0 then
Begin
Check(n);
//n is 0 based PrimeCount combinations of length n
inc(TotalUsedDigits[n+1]);
end;
end;
dec(ManifoldOfDigit[dgt]);
end;
procedure CheckAll(SumGoal:NativeInt);
var
i :NativeInt;
begin
setlength(CardString,SumGoal);
IF sumGoal>cTotalSum then
EXIT;
fillchar(ManifoldOfDigit[0],SizeOf(ManifoldOfDigit),#0);
permcount:=0;
PrimeCount := 0;
For i := 1 to 9 do
AppendToSum(0,i,SumGoal-i);
writeln('PrimeCount of generated numbers with digits sum of ',SumGoal,' are ',permcount);
writeln('Propably primes ',PrimeCount);
writeln;
end;
var
T1,T0 : Int64;
SumGoal: NativeInt;
BEGIN
writeln('GMP-Version ',gmp.version);
mpz_init_set_ui(z,0);
T0 := GetTickCount64;
For SumGoal := 25 to 25 do
Begin
CheckAll(SumGoal);
T1 := GetTickCount64;Writeln((T1-T0)/1000:7:3,' s');
T0 := T1;
end;
mpz_clear(z);
END.
- Output:
//Runnning on TIO.RUN GMP-Version 6.1.2 PrimeCount of generated numbers with digits sum of 25 are 10488498 Propably primes 1525141 9.932 s .... Free Pascal Compiler version 3.0.4 [2018/07/13] for x86_64 Copyright (c) 1993-2017 by Florian Klaempfl and others Target OS: Linux for x86-64 Compiling .code.tio.pp Linking .bin.tio /usr/bin/ld: warning: link.res contains output sections; did you forget -T? 204 lines compiled, 0.2 sec Real time: 10.135 s User time: 10.027 s Sys. time: 0.052 s CPU share: 99.45 % Exit code: 0
Perl
use strict;
use warnings;
use feature 'say';
use List::Util 'sum';
use ntheory 'is_prime';
my($limit, @p25) = 5000;
is_prime($_) and 25 == sum(split '', $_) and push @p25, $_ for 1..$limit;
say @p25 . " primes < $limit with digital sum 25:\n" . join ' ', @p25;
- Output:
17 primes < 5000 with digital sum 25: 997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Phix
function sum25(integer p) return sum(sq_sub(sprint(p),'0'))=25 end function sequence res = filter(get_primes_le(5000),sum25) string r = join(shorten(apply(res,sprint),"",4)) printf(1,"%d sum25 primes less than 5000 found: %s\n",{length(res),r})
- Output:
17 sum25 primes less than 5000 found: 997 1699 1789 1879 ... 4597 4759 4957 4993
Stretch goal
without js include mpfr.e atom t0 = time(), t1 = time()+1 mpz pz = mpz_init(0) function sum25(string p, integer rem, res=0) if rem=0 then if find(p[$],"1379") then -- (saves 13s) mpz_set_str(pz,p) if mpz_prime(pz) then res += 1 if platform()!=JS and time()>t1 then progress("%d, %s...",{res,p}) t1 = time()+1 end if end if end if else for i=1 to min(rem,9) do res = sum25(p&'0'+i,rem-i,res) end for end if return res end function printf(1,"There are %,d sum25 primes that contain no zeroes\n",sum25("",25)) ?elapsed(time()-t0)
- Output:
There are 1,525,141 sum25 primes that contain no zeroes "1 minute and 27s"
Note this works under pwa/p2js but you would get to stare at a blank screen for 8½ minutes with 100% cpu, hence it has been marked "without js".
Python
'''Primes with a decimal digit sum of 25'''
from itertools import takewhile
# primesWithGivenDigitSum :: Int -> Int -> [Int]
def primesWithGivenDigitSum(below, n):
'''Primes below a given value with
decimal digits sums equal to n.
'''
return list(
takewhile(
lambda x: below > x,
(
x for x in primes()
if n == sum(int(c) for c in str(x))
)
)
)
# ------------------------- TEST -------------------------
# main :: IO ()
def main():
'''Test'''
matches = primesWithGivenDigitSum(5000, 25)
print(
str(len(matches)) + (
' primes below 5000 with a decimal digit sum of 25:\n'
)
)
print(
'\n'.join([
' '.join([str(x).rjust(4, ' ') for x in xs])
for xs in chunksOf(4)(matches)
])
)
# ----------------------- GENERIC ------------------------
# chunksOf :: Int -> [a] -> [[a]]
def chunksOf(n):
'''A series of lists of length n, subdividing the
contents of xs. Where the length of xs is not evenly
divible, the final list will be shorter than n.
'''
def go(xs):
return (
xs[i:n + i] for i in range(0, len(xs), n)
) if 0 < n else None
return go
# primes :: [Int]
def primes():
''' Non-finite sequence of prime numbers.
'''
n = 2
dct = {}
while True:
if n in dct:
for p in dct[n]:
dct.setdefault(n + p, []).append(p)
del dct[n]
else:
yield n
dct[n * n] = [n]
n = 1 + n
# MAIN ---
if __name__ == '__main__':
main()
- Output:
17 primes below 5000 with a decimal digit sum of 25: 997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Quackery
eratosthenes
and isprime
are defined at Sieve of Eratosthenes#Quackery.
5000 eratosthenes
[ 0
[ over while
swap 10 /mod
rot + again ]
nip ] is digitsum ( n --> n )
[] 5000 times
[ i^ isprime not if done
i^ digitsum 25 = if
[ i^ join ] ]
echo
- Output:
[ 997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 ]
Raku
unit sub MAIN ($limit = 5000);
say "{+$_} primes < $limit with digital sum 25:\n{$_».fmt("%" ~ $limit.chars ~ "d").batch(10).join("\n")}",
with ^$limit .grep: { .is-prime and .comb.sum == 25 }
- Output:
17 primes < 5000 with digital sum 25: 997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
REXX
This REXX version allows the following to be specified on the command line:
- the high number (HI)
- the number of columns shown per line (COLS)
- the target sum (TARGET)
/*REXX pgm finds and displays primes less than HI whose decimal digits sum to TARGET.*/
parse arg hi cols target . /*obtain optional argument from the CL.*/
if hi=='' | hi=="," then hi= 5000 /*Not specified? Then use the default.*/
if cols=='' | cols=="," then cols= 10 /* " " " " " " */
if target=='' | target=="," then target= 25 /* " " " " " " */
call genP /*build array of semaphores for primes.*/
w= 10 /*width of a number in any column. */
title= ' primes that are < ' commas(hi) " and whose decimal digits sum to " ,
commas(target)
if cols>0 then say ' index │'center(title, 1 + cols*(w+1) )
if cols>0 then say '───────┼'center("" , 1 + cols*(w+1), '─')
found= 0; idx= 1 /*define # target primes found and IDX.*/
$= /*list of target primes found (so far).*/
do j=1 for # /*examine all the primes generated. */
if sumDigs(@.j)\==target then iterate /*Is sum≡target sum? No, then skip it.*/
found= found + 1 /*bump the number of target primes. */
if cols<1 then iterate /*Build the list (to be shown later)? */
c= commas(@.j) /*maybe add commas to the number. */
$= $ right(c, max(w, length(c) ) ) /*add a prime ──► list, allow big #'s.*/
if found//cols\==0 then iterate /*have we populated a line of output? */
say center(idx, 7)'│' substr($, 2); $= /*display what we have so far (cols). */
idx= idx + cols /*bump the index count for the output*/
end /*j*/
if $\=='' then say center(idx, 7)"│" substr($, 2) /*possible display residual output.*/
if cols>0 then say '───────┴'center("" , 1 + cols*(w+1), '─')
say
say 'Found ' commas(found) title
exit 0 /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
commas: parse arg ?; do jc=length(?)-3 to 1 by -3; ?=insert(',', ?, jc); end; return ?
/*──────────────────────────────────────────────────────────────────────────────────────*/
genP: !.= 0 /*placeholders for primes' semaphores. */
@.1=2; @.2=3; @.3=5; @.4=7; @.5=11; @.6=13 /*define some low primes. */
!.2=1; !.3=1; !.5=1; !.7=1; !.11=1; @.13=1 /* " " " primes' semaphores. */
#= 6; sq.#= @.# ** 2 /*number of primes so far; prime². */
/* [↓] generate more primes ≤ high.*/
do j=@.#+2 by 2 to hi /*find odd primes from here on. */
parse var j '' -1 _ /*obtain the last decimal digit of J. */
if _==5 then iterate; if j// 3==0 then iterate /*J ÷ by 5? J ÷ by 3? */
if j//7==0 then iterate; if j//11==0 then iterate /*" " " 7? " " " 11? */
do k=6 while sq.k<=j /* [↓] divide by the known odd primes.*/
if j // @.k == 0 then iterate j /*Is J ÷ X? Then not prime. ___ */
end /*k*/ /* [↑] only process numbers ≤ √ J */
#= #+1; @.#= j; sq.#= j*j; !.j= 1 /*bump # of Ps; assign next P; P²; P# */
end /*j*/; return
/*──────────────────────────────────────────────────────────────────────────────────────*/
sumDigs: parse arg x 1 s 2 '' -1 z; L= length(x); if L==1 then return s; s= s + z
do m=2 for L-2; s= s + substr(x, m, 1); end; return s
- output when using the default inputs:
index │ primes that are < 5,000 and whose decimal digits sum to 25 ───────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────── 1 │ 997 1,699 1,789 1,879 1,987 2,689 2,797 2,887 3,499 3,697 11 │ 3,769 3,877 3,967 4,597 4,759 4,957 4,993 ───────┴─────────────────────────────────────────────────────────────────────────────────────────────────────────────── Found 17 primes that are < 5,000 and whose decimal digits sum to 25
- output when using the input of: 1000000 0
Found 6,198 primes that are < 1,000,000 and whose decimal digits sum to 25
Ring
load "stdlib.ring"
see "working..." + nl
decimals(0)
row = 0
num = 0
nr = 0
numsum25 = 0
limit1 = 25
limit2 = 5000
for n = 1 to limit2
if isprime(n)
bool = sum25(n)
if bool = 1
row = row + 1
see "" + n + " "
if (row%5) = 0
see nl
ok
ok
ok
next
see nl + "Found " + row + " sum25 primes below 5000" + nl
time1 = clock()
see nl
row = 0
while true
num = num + 1
str = string(num)
for m = 1 to len(str)
if str[m] = 0
loop
ok
next
if isprime(num)
bool = sum25(num)
if bool = 1
nr = num
numsum25 = numsum25 + 1
ok
ok
time2 = clock()
time3 = (time2-time1)/1000/60
if time3 > 30
exit
ok
end
see "There are " + numsum25 + " sum25 primes that contain no zeroes (during 30 mins)" + nl
see "The last sum25 prime found during 30 mins is: " + nr + nl
see "time = " + time3 + " mins" + nl
see "done..." + nl
func sum25(n)
sum = 0
str = string(n)
for n = 1 to len(str)
sum = sum + number(str[n])
next
if sum = limit1
return 1
ok
- Output:
working... 997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 Found 17 sum25 primes below 5000 There are 1753 sum25 primes that contain no zeroes (during 30 mins) The last sum25 prime found during 30 mins is: 230929 time = 30 mins done...
RPL
∑DIGITS
is defined at Sum digits of an integer
≪ { } 799 @ 799 is the smallest integer whose digits sum equals 25, and is not prime : 799 = 47 * 17 DO NEXTPRIME IF DUP ∑DIGITS 25 == THEN SWAP OVER + SWAP END UNTIL DUP 5000 > END DROP ≫ 'TASK' STO
- Output:
1: {997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993}
Ruby
require 'prime'
def digitSum(n)
sum = 0
while n > 0
sum += n % 10
n /= 10
end
return sum
end
for p in Prime.take_while { |p| p < 5000 }
if digitSum(p) == 25 then
print p, " "
end
end
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Sidef
Simple solution:
5000.primes.grep { .sumdigits == 25 }.say
Generate such primes from digits (asymptotically faster):
func generate_from_prefix(limit, digitsum, p, base, digits, t=p) {
var seq = [p]
digits.each {|d|
var num = (p*base + d)
num <= limit || return seq
var sum = (t + d)
sum <= digitsum || return seq
seq << __FUNC__(limit, digitsum, num, base, digits, sum)\
.grep { .is_prime }...
}
return seq
}
func primes_with_digit_sum(limit, digitsum = 25, base = 10, digits = @(^base)) {
digits.grep { _ > 0 }\
.map { generate_from_prefix(limit, digitsum, _, base, digits)... }\
.grep { .sumdigits(base) == digitsum }\
.sort
}
say primes_with_digit_sum(5000)
- Output:
[997, 1699, 1789, 1879, 1987, 2689, 2797, 2887, 3499, 3697, 3769, 3877, 3967, 4597, 4759, 4957, 4993]
Tcl
Could be made prettier with the staple helper proc lfilter.
package require Tcl 8.5
package require math::numtheory
namespace path ::tcl::mathop
puts [lmap x [math::numtheory::primesLowerThan 5000] {
if {[+ {*}[split $x {}]] == 25} {set x} else continue
}]
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Wren
Basic
import "./math" for Int
import "./fmt" for Fmt
var sumDigits = Fn.new { |n|
var sum = 0
while (n > 0) {
sum = sum + (n % 10)
n = (n/10).floor
}
return sum
}
var primes = Int.primeSieve(4999).where { |p| p >= 997 }
var primes25 = []
for (p in primes) {
if (sumDigits.call(p) == 25) primes25.add(p)
}
System.print("The %(primes25.count) primes under 5,000 whose digits sum to 25 are:")
Fmt.tprint("$,6d", primes25, 6)
- Output:
The 17 primes under 5,000 whose digits sum to 25 are: 997 1,699 1,789 1,879 1,987 2,689 2,797 2,887 3,499 3,697 3,769 3,877 3,967 4,597 4,759 4,957 4,993
Stretch
Run time is about 25.5 seconds.
import "./gmp" for Mpz
import "./fmt" for Fmt
var z = Mpz.new()
var countAll // recursive
countAll = Fn.new { |p, rem, res|
if (rem == 0) {
var b = p[-1]
if ("1379".contains(b)) {
if (z.setStr(p).probPrime(15) > 0) res = res + 1
}
} else {
for (i in 1..rem.min(9)) {
res = countAll.call(p + i.toString, rem - i, res)
}
}
return res
}
var n = countAll.call("", 25, 0)
Fmt.print("There are $,d primes whose digits sum to 25 and include no zeros.", n)
- Output:
There are 1,525,141 primes whose digits sum to 25 and include no zeros.
XPL0
func IsPrime(N); \Return 'true' if N is prime
int N, I;
[if N <= 2 then return N = 2;
if (N&1) = 0 then \even >2\ return false;
for I:= 3 to sqrt(N) do
[if rem(N/I) = 0 then return false;
I:= I+1;
];
return true;
];
func SumDigits(N); \Return sum of digits in N
int N, Sum;
[Sum:= 0;
repeat N:= N/10;
Sum:= Sum + rem(0);
until N=0;
return Sum;
];
int Cnt, N;
[Cnt:= 0;
for N:= 2 to 5000-1 do
if IsPrime(N) & SumDigits(N) = 25 then
[IntOut(0, N);
Cnt:= Cnt+1;
if rem(Cnt/5) then ChOut(0, 9\tab\) else CrLf(0);
];
CrLf(0);
IntOut(0, Cnt);
Text(0, " primes whose sum of digits is 25.
");
]
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993 17 primes whose sum of digits is 25.
Zig
const std = @import("std");
fn isPrime(n: u64) bool {
if (n < 2) return false;
if (n % 2 == 0) return n == 2;
if (n % 3 == 0) return n == 3;
var d: u64 = 5;
while (d * d <= n) {
if (n % d == 0) return false;
d += 2;
if (n % d == 0) return false;
d += 4;
}
return true;
}
fn digitSum(n_: u64) u16 {
var n = n_; // parameters are immutable, copy to var
var sum: u16 = 0;
while (n != 0) {
sum += @truncate(u16, n % 10);
n /= 10;
}
return sum;
}
pub fn main() !void {
var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
defer arena.deinit();
var result = std.ArrayList(u64).init(arena.allocator());
defer result.deinit();
{
var n: u64 = 3;
while (n <= 5000) : (n += 2)
if (digitSum(n) == 25 and isPrime(n))
try result.append(n);
}
const stdout = std.io.getStdOut().writer();
for (result.items, 0..) |n, i|
_ = try stdout.print("{d:4}{s}", .{ n, if ((i + 1) % 6 == 0) "\n" else " " });
}
- Output:
997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
- Draft Programming Tasks
- Prime Numbers
- 11l
- Action!
- Action! Sieve of Eratosthenes
- Ada
- ALGOL 68
- ALGOL W
- AppleScript
- Arturo
- AWK
- BASIC
- BASIC256
- C
- C++
- GMP
- D
- Delphi
- System.SysUtils
- PrimTrial
- EasyLang
- F Sharp
- Factor
- Forth
- FreeBASIC
- Frink
- Go
- GMP(Go wrapper)
- Haskell
- J
- Java
- JavaScript
- Jq
- Julia
- Kotlin
- Ksh
- Mathematica
- Wolfram Language
- Nanoquery
- Nim
- Bignum
- Pascal
- Perl
- Ntheory
- Phix
- Phix/mpfr
- Python
- Quackery
- Raku
- REXX
- Ring
- RPL
- Ruby
- Sidef
- Tcl
- Tcllib
- Wren
- Wren-math
- Wren-fmt
- Wren-gmp
- XPL0
- Zig