Primes whose sum of digits is 25: Difference between revisions

From Rosetta Code
Content added Content deleted
(Added Delphi example)
Line 161: Line 161:
load "stdlib.ring"
load "stdlib.ring"


see "working..." + nl
decimals(0)
row = 0
row = 0
num = 0
nr = 0
limit1 = 25
limit1 = 25
limit2 = 5000
limit2 = 5000
Line 177: Line 181:
ok
ok
next
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 = nr + 1
ok
ok
time2 = clock()
time3 = (time2-time1)/1000/60
if time3 > 30
exit
ok
end

see "There are " + nr + " sum25 primes that contain no zeroes" + nl
see "time = " + time3 + " mins" + nl
see "done..." + nl


func sum25(n)
func sum25(n)
Line 190: Line 225:
{{out}}
{{out}}
<pre>
<pre>
working...
997 1699 1789 1879 1987
997 1699 1789 1879 1987
2689 2797 2887 3499 3697
2689 2797 2887 3499 3697
3769 3877 3967 4597 4759
3769 3877 3967 4597 4759
4957 4993
4957 4993
Found 17 sum25 primes below 5000

There are 1555 sum25 primes that contain no zeroes
time = 30 mins
done...
</pre>
</pre>

Revision as of 14:47, 21 March 2021

Primes whose sum of digits is 25 is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
Task

Show primes which sum of digits is 25
Let 0 < n < 5000

Stretch goal

Show the total number of all such primes that do not contain any zeroes (997 <= n <= 1,111,111,111,111,111,111,111,111).

ALGOL W

<lang algolw>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.</lang>

Output:
  997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993
Found 17 sum25 primes below 5000

Delphi

Library: PrimTrial
Translation of: Ring

<lang 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.</lang>

Output:
 997 1699 1789 1879 1987
2689 2797 2887 3499 3697
3769 3877 3967 4597 4759
4957 4993

Phix

<lang 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})</lang>

Output:
17 sum25 primes less than 5000 found: 997 1699 1789 1879 ... 4597 4759 4957 4993

Stretch goal

Library: Phix/mpfr

<lang Phix>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 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)</lang>

Output:
There are 1,525,141 sum25 primes that contain no zeroes
"1 minute and 27s"

Raku

<lang perl6>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 }</lang>
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

Ring

<lang ring> load "stdlib.ring"

see "working..." + nl decimals(0) row = 0 num = 0 nr = 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 = nr + 1
         ok
     ok
     time2 = clock()
     time3 = (time2-time1)/1000/60
     if time3 > 30
        exit
     ok

end

see "There are " + nr + " sum25 primes that contain no zeroes" + 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

</lang>

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 1555 sum25 primes that contain no zeroes
time = 30 mins
done...