hdu 1124 Factorial （快速求n!末尾0的个数）

思路：f(n)表示n!的末尾0的个数，则

f(n) = n/5 + f(n/5)  n >= 5

f(n) = 0; n < 5

证明：点击

代码：

#include <iostream>#include <stdio.h>#include <string.h>#include <math.h>#include <stdlib.h>#include <map>#include <set>#include <vector>#include <stack>#include <queue>#include <algorithm>using namespace std;#define mst(a,b) memset(a,b,sizeof(a))#define eps 10e-8const int MAX_ = 10010;const int N = 100010;const int INF = 0x7fffffff;int a[MAX_];int find(int n){    if(n < 5)return 0;    return n/5 + find(n/5);}int main(){int n, T;scanf("%d", &T);while(T--){        scanf("%d", &n);        int ans = find(n);        printf("%d\n", ans);    }return 0;}