hdu 5778 abs

#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<algorithm>
#define LL long long
using namespace std;
bool devide(LL x){
	for(LL i=2;i*i<=x;++i){
		if(x%i==0){
			x/=i;
			if(x%i==0) return false;	
		}	
	}
	return true;	
}
int main(){
	int t;
	scanf("%d",&t);
	while(t--){
		LL x;
		LL ans;
		scanf("%I64d",&x);
		if(x<=4){
			printf("%I64d\n",4-x);
			continue;	
		}
		LL tmp=(LL)sqrt(x);
		for(int i=0;;++i){
			LL tmpp=tmp+i;
			if(tmpp*tmpp>=x&&devide(tmpp)){
				ans=abs(tmpp*tmpp-x);
				break;	
			}	
		}
		for(int i=0;;++i){
			LL tmpp=tmp-i;
			if(tmpp*tmpp<=x&&devide(tmpp)){
				ans=min(ans,abs(tmpp*tmpp-x));
				break;	
			}	
		}
		printf("%I64d\n",ans);
	}
	system("pause");
	return 0;	
}

##总结

1. 10的9次方级别内两个素数的最大距离为300