Goldbach's Conjecture

题目链接

#include<iostream>
#include<cstdio>//pku不支持万能头吗QAQ
using namespace std;
int ifp[1000010],p[1000010];
int main()
{
	int cnt=0,n;
	ifp[1]=1;
	for(int i=2;i<=1000000;i++)
	{
		if(!ifp[i]) p[++cnt]=i;
		for(int j=1;j<=cnt&&i*p[j]<=1000000;j++)//别忘了i*p[j]<=n
		{
			ifp[i*p[j]]=1;
			if(!i%p[j]) break;
		}
	}
	cin>>n;
	while(n!=0)
	{
		for(int i=1;i<=n/2;i++)//直接枚举求出来的i和n-i肯定就是差值最大的
		{
			if(!ifp[i]&&!ifp[n-i])
			{
				cout<<n<<" = "<<i<<" + "<<n-i<<"
";
				break;
			}
		}
		cin>>n;
	}
     // Goldbach’s conjecture is wrong滑稽
}