1439 统计素数个数

#include<iostream>#include<cmath>using namespace std;bool sushu(int n){for (int i = 2; i <= sqrt(n); i++)if (n%i == 0)return 0;return 1;}int main(){int l, r,num;while (cin >> l >> r){num = 0;for (int i = l; i <= r;i++)if (i>=2)//0和1单独判断下if (sushu(i))num++;cout << num << endl;}return 0;}