Magnanimous numbers: Difference between revisions
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391st through 400th magnanimous numbers:
486685 488489 515116 533176 551558 559952 595592 595598 600881 602081
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=={{header|Java}}==
<lang java>
import java.util.ArrayList;
import java.util.List;
public class MagnanimousNumbers {
public static void main(String[] args) {
runTask("Find and display the first 45 magnanimous numbers.", 1, 45);
runTask("241st through 250th magnanimous numbers.", 241, 250);
runTask("391st through 400th magnanimous numbers.", 391, 400);
}
private static void runTask(String message, int startN, int endN) {
int count = 0;
List<Integer> nums = new ArrayList<>();
for ( int n = 0 ; count < endN ; n++ ) {
if ( isMagnanimous(n) ) {
nums.add(n);
count++;
}
}
System.out.printf("%s%n", message);
System.out.printf("%s%n%n", nums.subList(startN-1, endN));
}
private static boolean isMagnanimous(long n) {
if ( n >= 0 && n <= 9 ) {
return true;
}
long q = 11;
for ( long div = 10 ; q >= 10 ; div *= 10 ) {
q = n / div;
long r = n % div;
if ( ! isPrime(q+r) ) {
return false;
}
}
return true;
}
private static final int MAX = 100_000;
private static final boolean[] primes = new boolean[MAX];
private static boolean SIEVE_COMPLETE = false;
private static final boolean isPrimeTrivial(long test) {
if ( ! SIEVE_COMPLETE ) {
sieve();
SIEVE_COMPLETE = true;
}
return primes[(int) test];
}
private static final void sieve() {
// primes
for ( int i = 2 ; i < MAX ; i++ ) {
primes[i] = true;
}
for ( int i = 2 ; i < MAX ; i++ ) {
if ( primes[i] ) {
for ( int j = 2*i ; j < MAX ; j += i ) {
primes[j] = false;
}
}
}
}
// See http://primes.utm.edu/glossary/page.php?sort=StrongPRP
public static final boolean isPrime(long testValue) {
if ( testValue == 2 ) return true;
if ( testValue % 2 == 0 ) return false;
if ( testValue <= MAX ) return isPrimeTrivial(testValue);
long d = testValue-1;
int s = 0;
while ( d % 2 == 0 ) {
s += 1;
d /= 2;
}
if ( testValue < 1373565L ) {
if ( ! aSrp(2, s, d, testValue) ) {
return false;
}
if ( ! aSrp(3, s, d, testValue) ) {
return false;
}
return true;
}
if ( testValue < 4759123141L ) {
if ( ! aSrp(2, s, d, testValue) ) {
return false;
}
if ( ! aSrp(7, s, d, testValue) ) {
return false;
}
if ( ! aSrp(61, s, d, testValue) ) {
return false;
}
return true;
}
if ( testValue < 10000000000000000L ) {
if ( ! aSrp(3, s, d, testValue) ) {
return false;
}
if ( ! aSrp(24251, s, d, testValue) ) {
return false;
}
return true;
}
// Try 5 "random" primes
if ( ! aSrp(37, s, d, testValue) ) {
return false;
}
if ( ! aSrp(47, s, d, testValue) ) {
return false;
}
if ( ! aSrp(61, s, d, testValue) ) {
return false;
}
if ( ! aSrp(73, s, d, testValue) ) {
return false;
}
if ( ! aSrp(83, s, d, testValue) ) {
return false;
}
//throw new RuntimeException("ERROR isPrime: Value too large = "+testValue);
return true;
}
private static final boolean aSrp(int a, int s, long d, long n) {
long modPow = modPow(a, d, n);
//System.out.println("a = "+a+", s = "+s+", d = "+d+", n = "+n+", modpow = "+modPow);
if ( modPow == 1 ) {
return true;
}
int twoExpR = 1;
for ( int r = 0 ; r < s ; r++ ) {
if ( modPow(modPow, twoExpR, n) == n-1 ) {
return true;
}
twoExpR *= 2;
}
return false;
}
private static final long SQRT = (long) Math.sqrt(Long.MAX_VALUE);
public static final long modPow(long base, long exponent, long modulus) {
long result = 1;
while ( exponent > 0 ) {
if ( exponent % 2 == 1 ) {
if ( result > SQRT || base > SQRT ) {
result = multiply(result, base, modulus);
}
else {
result = (result * base) % modulus;
}
}
exponent >>= 1;
if ( base > SQRT ) {
base = multiply(base, base, modulus);
}
else {
base = (base * base) % modulus;
}
}
return result;
}
// Result is a*b % mod, without overflow.
public static final long multiply(long a, long b, long modulus) {
long x = 0;
long y = a % modulus;
long t;
while ( b > 0 ) {
if ( b % 2 == 1 ) {
t = x + y;
x = (t > modulus ? t-modulus : t);
}
t = y << 1;
y = (t > modulus ? t-modulus : t);
b >>= 1;
}
return x % modulus;
}
}
</lang>
{{out}}
<pre>
Find and display the first 45 magnanimous numbers.
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 14, 16, 20, 21, 23, 25, 29, 30, 32, 34, 38, 41, 43, 47, 49, 50, 52, 56, 58, 61, 65, 67, 70, 74, 76, 83, 85, 89, 92, 94, 98, 101, 110]
241st through 250th magnanimous numbers.
[17992, 19972, 20209, 20261, 20861, 22061, 22201, 22801, 22885, 24407]
391st through 400th magnanimous numbers.
[486685, 488489, 515116, 533176, 551558, 559952, 595592, 595598, 600881, 602081]
</pre>
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