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; else return false; }