题解 | rin和快速迭代

#include <stdio.h>
#include <math.h>

long long func(long long x) {
    long long root = sqrt(x), result = 0;
    for (long long i = 1; i <= root; ++i) {
        if (x % i == 0) {
            result += 2;
        }
    }
    if (x == root * root) {
        result -= 1;
    }
    return result;
}

int main() {
    long long n;
    int times = 0;
    scanf("%lld\n", &n);
    while (n != 2) {
        n = func(n);
        ++times;
    }
    printf("%d\n", times);
    return 0;
}