题目:hdu2098
代码一:105ms
#include<iostream>#include<cmath>using namespace std;int prime(int x){ int i; for(i=(int)sqrt(x);i>1;i--) if(x%i==0)return 0; return 1;}int main(){ int n,i,c; while(cin>>n&&n) { c=0; for(i=2;i<n/2;i++) { if(prime(i)&&prime(...