HDU-1299 Diophantus of Alexandria 素因子分解

一个需要进行转化的题目。

x = (n*(n+k))/k = n*n/k + n，最后求小于等于N且是N^2的因子的数的个数。

代码如下：

#include <cstdlib>

#include <cstdio>

#include <cstring>

#include <cmath>

#include <map>

using namespace std;



int N;

map<int,int>mp;

map<int,int>::iterator it;



int fun()

{

    int ret = 1;

    for (it = mp.begin(); it != mp.end(); ++it) {

        ret *= (1 + 2 * it->second);

    }

    return ret;

}



int main()

{

    int ca = 0, T, lim, sum;

    scanf("%d", &T);

    while (T--) {

        sum = 0;

        mp.clear();

        scanf("%d", &N);

        lim = (int)sqrt(N*1.);

        for (int i = 2; i <= lim; ++i) {

            while (N % i == 0) {

                ++mp[i];

                N /= i;

            }

        }

        printf("Scenario #%d:\n", ++ca);

        sum = fun();

        if (N != 1) {

            sum *= 3;

        }

        printf("%d\n\n", sum + 1 >> 1);

    }

    return 0;

}