Semi-Prime(set)

Prime Number Definition 
An integer greater than one is called a prime number if its only positive divisors (factors) are one and itself. For instance, 2, 11, 67, 89 are prime numbers but 8, 20, 27 are not.

Semi-Prime Number Definition 
An integer greater than one is called a semi-prime number if it can be decompounded to TWO prime numbers. For example, 6 is a semi-prime number but 12 is not.

Your task is just to determinate whether a given number is a semi-prime number.

 

素数定义

如果一个大于1的整数只有一个正整数（因子）是一个整数，那么它就称为素数。 例如，2,11,67,89是素数，但8,20,27不是。

半素数定义

如果一个大于1的整数可以分解为两个素数，则称其为一个半素数。 例如，6是一个半素数，但12不是。

你的任务只是确定一个给定的数字是否是一个半素数。

Input

There are several test cases in the input. Each case contains a single integer N (2 <= N <= 1,000,000)

 

输入中有几个测试用例。 每个案例包含一个整数N（2 <= N <= 1,000,000）

Output

One line with a single integer for each case. If the number is a semi-prime number, then output "Yes", otherwise "No".

 

一行每个案件都有一个整数。 如果数字是半素数，则输出“是”，否则输出“否”。

Sample Input

3
4
6
12

 

Sample OutputNo 
Yes 
Yes 
No 

 

what i have learned:

set search

 

#include<iostream>
#include<vector>
#include<set>
#include<cmath>
using namespace std;

vector<int> v;
set<int> s;

void pt(int a, int b)
{
    for(int i = a; i <= b; i++)
    {
        if(i != 2 && i % 2 == 0)
            continue;
        for(int j = 3; j * j <= i; j += 2)
        {
            if(i % j == 0)
                goto RL;
        }
        v.push_back(i);
        RL: continue;
    }
}

int main()
{
    pt(2, 500000);
    int i, j, p;
    for(int i = 0; i < v.size(); i++)
    {
        for(int j = 0; j < v.size(); j++)
        {
            p = v[i] * v[j];
            if(p < 1000000)
                s.insert(p);
            else
                break;
        }
    }

    int n;
    set<int>::iterator it;
    while(cin >> n)
    {
        it = s.find(n);
        if(it != s.end())
            cout << "Yes" << endl;
        else
            cout << "No" << endl;
    }
    return 0;
}