POJ 2368 Buttons

题目链接：http://poj.org/problem?id=2368

Bash game (巴什博弈）：当K是（L+1）的倍数时可以确保second player赢。所以这道题要找的就是在K的因子中有没有大于2的因子。代码如下：

#include <iostream>
#include <math.h>
#include <stdio.h>
#include <cstdio>
#include <algorithm>
#include <string.h>
#include <string>
#include <sstream>
#include <cstring>
#include <queue>
#include <vector>
#include <functional>
#include <cmath>
#include <set>
#define SCF(a) scanf("%d", &a)
#define IN(a) cin>>a
#define FOR(i, a, b) for(int i=a;i<b;i++)
#define Infinity 999999999
#define NInfinity -999999999
#define PI 3.14159265358979323846
typedef long long Int;
using namespace std;

int main()
{
    int K;
    int a;
    int factor[10010];
    while (SCF(K) != EOF)
    {
        int len = 0;
        for (a = 1; a*a <= K; a++)
        {
            if (K % a == 0)
            {
                factor[len++] = a;
                factor[len++] = K / a;
            }
        }
        sort(factor, factor + len);
        bool found = false;
        FOR(i, 0, len)
        {
            if (factor[i] > 2)
            {
                printf("%d\n", factor[i]-1);
                found = true;
                break;
            }
        }
        if (!found)
            printf("0\n");
    }
    return 0;
}