solution

欧拉函数法可以解决模幂运算

#include<stdio.h>
#include<math.h>
int main(){int a, m, n, r=1;scanf("%d%d%d", &a, &m, &n);while(m){if(m&1) r=(r*a)%n;a=(a*a)%n;m>>=1; }printf("%d", r);return 0;
}

给定伪代码的思想

#include<stdio.h>
#include<math.h>
int isPrime(int n){for(int i = 2; i <= sqrt(n); i++){if(n % i == 0) return 0;}return 1;
}
int gcd(int a, int b){int temp;while(a){temp = a;a = b % a;b = temp;}return b;
}
int main(){int a, m, n, count = 0, c = 1, z[35], num = 0, t;scanf("%d%d%d", &a, &m, &n);if(isPrime(n) && gcd(a, n) == 1 && m >= n){m%= n-1;} t = m;do{z[num++] = t % 2;t /= 2;if(z[num-1]) count++; }while(t != 0);for(int j = num - 1; j >= 0; j--){c = (c*c) % n;if(z[j]) c = (a*c) % n;}printf("%d %d", c, count);return 0;
}