poj2262

Goldbach's Conjecture

#include "math.h"#include "stdlib.h"#include<iostream>using namespace std;bool isprime(int x);int main(){int num;cin>>num;while(num!=0){int i;for(i=3;i<num/2+1;i++){if(isprime(i)&&isprime(num-i)){printf("%d = %d + %d/n",num,i,num-i);break;}}if(i==num/2+1)printf("Goldbach's conjecture is wrong/n");cin>>num;}return 0;}bool isprime(int x){int flag=1;if(x==2)return true;for(int j=2;j<=((int)sqrt((float)x))+1;j++){if(x%j==0){flag=0;break;}}if(flag==1)return true;elsereturn false;}