Primes whose sum of digits is 25: Difference between revisions
→{{header|C++}}
m (→{{header|C++}}: small modification certenty level 25-> 3 TIO.tun runtime) |
|||
Line 422:
Prime numbers 1-5000 whose digits sum to 25: 17
</pre>
=={{header|C}}==
<lang 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;
}</lang>
{{out}}
<pre>997 1699 1789 1879 1987 2689 2797 2887 3499 3697 3769 3877 3967 4597 4759 4957 4993</pre>
=={{header|C++}}==
| |||