URAL 2003. Simple Magic(数学啊 )

题目链接：http://acm.timus.ru/problem.aspx?space=1&num=2003

2003. Simple Magic

3
1
2
3

1

4
2
2
2
2

infinity

题意:

问是否能按照类似：array {2, 3, 3, 6} turns it into array {gcd(2, 3), gcd(2, 3), gcd(2, 6), gcd(3, 3), gcd(3, 6), gcd(3, 6)}, 的方式，求所给数组！

代码如下：

#include <cstdio>
#include <cmath>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define INF 0x3f3f3f3f
int a[10000047];
int main()
{
    int n;
    int num;
    while(~scanf("%d",&n))
    {
        memset(a, 0,sizeof(a));
        int ans = -INF;
        for(int i = 0; i < n; i++)
        {
            scanf("%d",&num);
            int k = sqrt(num*1.0);
            for(int i = 2; i <= k; i++)//质因子
            {
                if(num%i == 0)
                {
                    a[i]++;
                    ans = max(ans,a[i]);
                    while(1)
                    {
                        if(num%i == 0)
                        {
                            num/=i;
                        }
                        else
                        {
                            break;
                        }
                    }
                }
            }
            if(num != 1)
            {
                a[num]++;
            }
            ans = max(ans,a[num]);
        }
        if(ans == 1)
        {
            printf("1\n");
        }
        else if(ans == 2)
        {
            printf("2\n");
        }
        else if(ans == 0)
        {
            printf("0\n");
        }
        else
        {
            printf("infinity\n");
        }
    }
    return 0;
}

URAL 2003. Simple Magic(数学啊 )

原文：http://blog.csdn.net/u012860063/article/details/43737463