判断整数k（k<1000）能被两个质数相加的组合（低效率 求高效率的方法）

#include <iostream>
#include <string>
#include <stdio.h>
#include <cmath>
#include <vector>
using namespace std;
bool check(int n)
{
for (int i = 2; i < n; i++)
{
if (n%i == 0)
return false;
}
return true;
}

int count(int k)
{
int count = 0;
vector <int > myv;
for (int i = 2; i < 1000; i++)
{

if (check(i))
{
myv.push_back(i);
}
}

for(int i=0;i<myv.size();i++)
{
for (int j = i; j < myv.size(); j++)
{
if (myv[i] + myv[j] == k)
count++;
}
}

return count;

}

int main()
{

cout << count(5) << endl;

system("pause");
}