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Codefroces B. T-primes

http://codeforces.com/problemset/problem/230/B

B. T-primes
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

We know that prime numbers are positive integers that have exactly two distinct positive divisors. Similarly, we'll call a positive integer t Т-prime, if t has exactly three distinct positive divisors.

You are given an array of n positive integers. For each of them determine whether it is Т-prime or not.

Input

The first line contains a single positive integer, n (1 ≤ n ≤ 105), showing how many numbers are in the array. The next line contains n space-separated integers xi (1 ≤ xi ≤ 1012).

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is advised to use the cin, cout streams or the %I64d specifier.

Output

Print n lines: the i-th line should contain "YES" (without the quotes), if number xi is Т-prime, and "NO" (without the quotes), if it isn't.

Examples
Input
3
4 5 6
Output
YES
NO
NO
Note

The given test has three numbers. The first number 4 has exactly three divisors — 1, 2 and 4, thus the answer for this number is "YES". The second number 5 has two divisors (1 and 5), and the third number 6 has four divisors (1, 2, 3, 6), hence the answer for them is "NO".

只有三个因子的数,分析后即可得到1.本身,以及一个素数完全平方根

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
#include <cmath>
#include <set>
#include <map>
#include <algorithm>
using namespace std;
typedef long long ll;
ll a[1000006];
void get_prime()
{
    memset(a,0,sizeof(a));
    a[1]=1;
    for(int i=2;i<1000006;i++)
    {
        if(a[i]==0)
        {
            for(int j=2;j*i<1000006;j++)
            {
                a[j*i]=1;
            }
        }
    }
}
int main()
{
    ll x,n;
    cin>>n;
    get_prime();
    while(n--)
    {
        cin>>x;
        ll ans=sqrt(x);
        if(ans*ans==x && !a[ans])puts("YES");
        else puts("NO");
    }
    return 0;
} 

 

posted @ 2017-07-06 14:23  十年换你一句好久不见  阅读(305)  评论(0编辑  收藏  举报