Perfect Pth Powers

Description

We say that x is a perfect square if, for some integer b, x = b2. Similarly, x is a perfect cube if, for some integer b, x = b3. More generally, x is a perfect pth power if, for some integer b, x = bp. Given an integer x you are to determine the largest p such that x is a perfect pth power.
Input

Each test case is given by a line of input containing x. The value of x will have magnitude at least 2 and be within the range of a (32-bit) int in C, C++, and Java. A line containing 0 follows the last test case.
Output

For each test case, output a line giving the largest integer p such that x is a perfect pth power.
Sample Input

17
1073741824
25
0
Sample Output

1
30
2

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n,x;
int f=0;
ll power(ll x,int y) {
    ll res=1;
    while(y) {
        if(y&1) res*=x;
        x*=x;
        y>>=1;
    }
    return res;
}//快速幂 
int main() {
    while(true) {
        scanf("%lld",&n);
        if(n==0) break;
        if(n<0) {
            n=-n;
            for(ll i=31; i>=1; i-=2) {
                x=pow(n,1.0/i)+0.5;
                f=0;
                for(ll j=x-2; j<=x+1; j++) {
                    if(power(j,i)==n) {
                        printf("%lld\n",i);
                        f=1;
                        break;
                    }
                }
                if(f==1) break;
            }
        } else {
            for(ll i=32; i>=1; i--) {
                x=pow(n,1.0/i)+0.5;
                f=0;
                for(ll j=x-2; j<=x+1; j++) {
                    if(power(j,i)==n) {
                        printf("%lld\n",i);
                        f=1;
                        break;
                    }
                }
                if(f==1) break;
            }
        }
    }
    return 0;
}