POJ 2262 建素数表

筛选法建素数表，差值最大的就是为获得得第一个素数对，和2909一样的题目，改改就ac。

Memory: 1156K		Time: 110MS
Language: C++		Result: Accepted

#include <iostream>
#include <math.h>
using namespace std;
const int MAX=1000001;
bool Prime[MAX];
int N;
void SetPrimeTableQuick()
{
    int j;
    memset(Prime,false,sizeof(Prime));
    for(int i=2;i<MAX;i++){
        if(i%2)
            Prime[i]=true;
    }
    for(int i=3;i<=sqrt((double)MAX);i++){
        if(Prime[i]){
            for(j=i+i;j<MAX;j+=i)
                Prime[j]=false;
        }
    }
    Prime[2]=true;
}

void Process(int x)
{
    int a,b;
    for(int i=2;i<N;i++)
    {
        if(i>=x)
            break;
        if(!Prime[i])
            continue;
        int diff=x-i;
        if(Prime[diff])
        {
            a=diff<i?diff:i;
            b=x-a;
            break;
        }
    }
    printf("%d = %d + %d\n",x,a,b);
}
        
int main()
{
    SetPrimeTableQuick();
    while(scanf("%d",&N)!=EOF&&N)
    {
        Process(N);
    }
    return 0;
}