一.Description The most important part of a GSM network is so called Base Transceiver Station (BTS). These transceivers form the areas called cells (this term gave the name to the cellular phone) and every phone connects to the BTS with the strongest…

The most important part of a GSM network is so called Base Transceiver Station (BTS). These transceivers form the areas called cells (this term gave the name to the cellular phone) and every phone connects to the BTS with the strongest signal (in a l…

题意:求一个数的阶乘最后边有几个0. 解法:如果有0说明这个数含有2和5这两个因子,对于一个阶乘来说因子2的数量一定比5的数量多,所以只要算有几个5就可以了,依次算5的个数,25的个数,125的个数……n以下的数字里含有因子5的数的个数是⌊n / 5⌋,含有因子25的数的个数是⌊n / 25⌋,以此类推,但是不需要因为25是平方就乘2,只要加上这个数就可以了,因为算5的时候已经数过一次25了. 代码: #include<stdio.h> #include<iostream> #in…

class Solution {public: int trailingZeroes(int n) {            if(n<=0) return 0; int i=0;           int res=0; while(n){ res+=n/5; n=n/5; } return res;}}; 很神奇的,eg  125 125=25*5,相当于前前面有1,2,3,4,5,……,20,21,22,23,24,25  * 5 125/5 = 25 相当于前面变成0,0,0,0,1,……

POJ 1401 Factorial Time Limit:1500MS     Memory Limit:65536KB     64bit IO Format:%lld & %llu   Description The most important part of a GSM network is so called Base Transceiver Station (BTS). These transceivers form the areas called cells (this ter…

一.问题描述 给定一个正整数n,请计算n的阶乘n!末尾所含有“0”的个数.例如: 5!=120,其末尾所含有的“0”的个数为1: 10!= 3628800,其末尾所含有的“0”的个数为2: 20!= 2432902008176640000,其末尾所含有的“0”的个数为4. 二.算法分析 此类问题很显然属于数学问题,一定要找到其中的本质规律才能得到正确的数学模型. 两个大数字相乘,都可以拆分成多个质数相乘,而质数相乘结果尾数为0的,只可能是2*5.如果想到了这一点,那么就可以进一步想到:两个数相乘…

题目: 给定一个正整数n,请计算n的阶乘n!末尾所含有“0”的个数. 举例: 5!=120,其末尾所含有的“0”的个数为1: 10!= 3628800,其末尾所含有的“0”的个数为2: 20!= 2432902008176640000,其末尾所含有的“0”的个数为4 解题思路: 两个大数字相乘,都可以拆分成多个质数相乘,而质数相乘结果尾数为0的,只可能是2*5.如果想到了这一点,那么就可以进一步想到:两个数相乘尾数0的个数其实就是依赖于2和5因子的个数.又因为每两个连续数字就会有一个因子2,个数…

#include <stdio.h> #include <malloc.h> //计算1000!尾数零的个数 //扩展n!的尾数零的个数 //2^a * 5^b //obviously a>b //so count = b //5*1 5*2 .....5*200 200个 除以5 //1 2 3 4 5 .... 200 中 包含 5*(1,2,3,4,...40) 40个 除以5 //5*1 5*2 ..... 5*8 void calc1(int n){ ; ,t; f…

Factorial Time Limit: 1500MS   Memory Limit: 65536K Total Submissions: 15137   Accepted: 9349 Description The most important part of a GSM network is so called Base Transceiver Station (BTS). These transceivers form the areas called cells (this term…

链接:http://poj.org/problem?id=1401 题意:计算N!的末尾0的个数 思路:算数基本定理 有0,分解为2*5,寻找2*5的对数,2的因子个数大于5,转化为寻找因子5的个数.又有算数基本定理: n!在素数因子分解中p的幂为[n/p]+[n/p2]+[n/p3]+... 同时最大次数不会超过logpn.通过换底公式,有ln(n)/ln(p) 代码:(51Nod去掉t循环即可) #include <iostream> #include <math.h> usi…