C++验证哥德巴赫猜想

Question

Answer 1

供参考：

#include<stdio.h>

int  isPrime(int n)
{
    int i;
    if(n<=3) return n>1;
    for(i=2;i*i<=n;i++)
       if(n%i == 0) return 0;
    return 1;
}

int main()
{
    int i,n,flg=0;
    scanf("%d",&n);
    if(n<4 || n>4000 || n%2!=0){
       printf("INPUT ERROR\n");
       return 1;
    }
    for(i = 2; i <= n/2; i++){
        if(isPrime(i) && isPrime(n-i)){
           printf("%-d=%-d+%-d\n",n,i,n-i);//输出
           flg=1;
           break;
        }
    }
    if(flg==0)printf("it is wrong.\n");
    
    return 0;
}