Squarefree number(欧拉筛)

6071: Squarefree number

时间限制(普通/Java):1000MS/3000MS     内存限制:65536KByte
总提交: 49            测试通过:24

描述

 

In mathematics, a squarefree number is one which is divisible by no perfect squares, except 1. For example, 10 is square-free but 18 is not, as it is divisible by 9 = 3^2. Now you need to determine whether an integer is squarefree or not.

输入

 

The first line contains an integer T indicating the number of test cases.
For each test case, there is a single line contains an integer N.

Technical Specification

1. 1 <= T <= 20
2. 2 <= N <= 10^18

输出

 

For each test case, output the case number first. Then output "Yes" if N is squarefree, "No" otherwise.

 

样例输入

2 30 75

样例输出

 

Case 1: Yes
Case 2: No

#include <bits/stdc++.h>
#define ll long long
using namespace std;

int t,num;
ll n;
const int maxn=1e6+6;
int primer[maxn];
int check[maxn];

void getprime(){
    check[0]=check[1]=1;
    for(int i=2;i<=maxn;i++){
        if(!check[i]) primer[num++]=i;
        for(int j=0;j<num;j++){
            if(i*primer[j]>maxn) break;
            check[i*primer[j]]=1;
            if(i%primer[j]==0) break;
        }
    }
}

int main(){
    ios::sync_with_stdio(false);
    int jishu=0;
    getprime();
    cin>>t;
    while(t--){
        cin>>n;
        bool flag=false;
        for(int i=0;i<num;i++){
            int ee=0;
            while(n%primer[i]==0){
                n/=primer[i];
                ee++;
            }
            if(ee>=2)
                flag=true;
            if(n==1) break;
        }
        if(flag) cout << "Case " << ++jishu << ": No" << endl;
        else{
            if(n!=1){
                ll shu=sqrt(n);
                if(shu*shu==n) cout << "Case " << ++jishu << ": No" << endl;
                else cout << "Case " << ++jishu << ": Yes" << endl;
            }
            else cout << "Case " << ++jishu << ": Yes" << endl;
        }
    }
    return 0;



}