（精）第三届河南省acm（素数）（1不是素数）

#include<iostream>#include<stdio.h>#include<math.h>using namespace std;#define MAX 3000//先求出来素数。int isS(int num){int i=2;for(i=2;i<=sqrt(num);i++){if(num%i==0){return 0;}}return 1;}int sushu[MAX];int main(){//freopen("in.txt","r",stdin);int i,j;sushu[0]=0;sushu[1]=1;for(i=2;i<MAX;i++){if(isS(i)){sushu[i]=1;}}int casen;scanf("%d",&casen);while(casen--){int num;scanf("%d",&num);int i=0;int qian=num;int hou=num;int flag=0;if(num==1){cout<<"2"<<endl;continue;}if(sushu[num]==1){cout<<num<<endl;flag=1;}while(flag==0){////向前走qian++;if(sushu[qian]==1){cout<<qian<<endl;flag=1;break;}//向后走hou--;if(sushu[hou]==1){cout<<hou<<endl;flag=1;break;}}}return 0;}