Given an integer n, return the number of trailing zeroes in n!. Note: Your solution should be in logarithmic time complexity. 思路:编程之美里有,就是找因子5的个数. int trailingZeroes(int n) { ; ) { ans += n / ; n /= ; } return ans; }…

题目描述: Given an integer n, return the number of trailing zeroes in n!. Note: Your solution should be in logarithmic time complexity. 解题思路: 这个题目给的评级是easy,其实只要想到要求n!中0的个数,能够得到0的只有:2,4,5,10,100....而这里面又以5最为稀缺,所以说我们可以得出阶乘的最终结果中的0的数量等于因子中5的数量,比如说10,阶乘含两个0,…

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place. 思路:不能用额外空间,就用矩阵的第一行和第一列来标记这一行或这一列是否需要置0. 用两个bool量记录第一行和第一列是否需要置0 大神的代码和我的代码都是这个思路,但是我在画0的时候是行列分开处理的,大神的代码是一起处理的 void setZeroes(vector<vector<int> > &…

Reverse a singly linked list. 思路:没啥好说的.秒... ListNode* reverseList(ListNode* head) { ListNode * rList = NULL, * tmp = NULL; while(head != NULL) { tmp = rList; rList = head; head = head->next; rList->next = tmp; } return rList; }…

The count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ... 1 is read off as "one 1" or 11.11 is read off as "two 1s" or 21.21 is read off as "one 2, then one 1" or 1211. Given an…

Write a function to find the longest common prefix string amongst an array of strings. 思路:找最长公共前缀 常规方法 string longestCommonPrefix(vector<string> &strs) { ) return ""; ) ]; string ans; ; ) { ; i < strs.size(); i++) { ].size() <= n…

写在前面   老粉丝可能知道现阶段的LeetCode刷题将按照某一个特定的专题进行,之前的[贪心算法]已经结束,虽然只有三个题却包含了简单,中等,困难这三个维度,今天介绍的是第二个专题[数组] 数组(Array)是一种线性表数据结构.它用一组连续的内存空间,来存储一组具有相同类型的数据.在每一种编程语言中,基本都会有数组这种数据类型.不过,它不仅仅是一种编程语言中的数据类型,还是一种最基础的数据结构. 贪心算法回顾: [LeetCode]贪心算法--买卖股票的最佳时机II(122) [LeetC…

Given an integer n, return the number of trailing zeroes in n!. Note: Your solution should be in logarithmic time complexity. 题目标签:Math 题目要求我们找到末尾0的数量. 只有当有10的存在,才会有0,比如 2 * 5 = 10; 4 * 5 = 20; 5 * 6 = 30; 5 * 8 = 40 等等,可以发现0 和 5 的联系. 所以这一题也是在问 n 里有多…

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by…

Single Number 题目 Given an array of integers, every element appears twice except for one. Find that single one.      Note:      Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? 思路: 为了满足时间和空间复杂度…