快速切题 sgu113 Nearly prime numbers 难度:0

113. Nearly prime numbers

time limit per test: 0.25 sec. 
memory limit per test: 4096 KB

 

Nearly prime number is an integer positive number for which it is possible to find such primes P₁ and P₂ that given number is equal to P₁*P₂. There is given a sequence on N integer positive numbers, you are to write a program that prints “Yes” if given number is nearly prime and “No” otherwise.

 

Input

Input file consists of N+1 numbers. First is positive integer N (1£N£10). Next N numbers followed by N. Each number is not greater than 10⁹. All numbers separated by whitespace(s).

 

Output

Write a line in output file for each number of given sequence. Write “Yes” in it if given number is nearly prime and “No” in other case.

 

Sample Input

1
6

Sample Output

Yes

思路:nearly prime数只能有两个质因数

#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
int n,num;
bool nearlyprime(){
    int cnt=0;
    int r=sqrt((double)num);
    if((num&1)==0){
        while((num&1)==0){
            num>>=1;
            cnt++;
            if(cnt>2)return false;
        }
    }
    for(int i=3;i<=r;i+=2){
        if(num%i==0){
            while(num%i==0){
                num/=i;
                cnt++;
                if(cnt>2)return false;
            }
        }
    }
    if(num!=1)cnt++;
    return cnt==2;
}
int main(){
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        scanf("%d",&num);
        if(nearlyprime())puts("Yes");
        else puts("No");
    }
    return 0;
}