Given an input string, reverse the string word by word. For example, Given s = "the sky is blue", return "blue is sky the". Have you met this question in a real interview?     Clarification What constitutes a word? A sequence of non-sp…

345. Reverse Vowels of a String[easy] Write a function that takes a string as input and reverse only the vowels of a string. Example 1:Given s = "hello", return "holle". Example 2:Given s = "leetcode", return "leotcede&q…

Write a function that takes a string as input and reverse only the vowels of a string. Example 1: Input: "hello" Output: "holle" Example 2: Input: "leetcode" Output: "leotcede" Note:The vowels does not include the l…

344. Reverse String[easy] Write a function that takes a string as input and returns the string reversed. Example:Given s = "hello", return "olleh". 解法一: class Solution { public: string reverseString(string s) { , end = s.length() - ; w…

557. Reverse Words in a String III[easy] Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order. Example 1: Input: "Let's take LeetCode contest" Output:…

206. Reverse Linked List[easy] Reverse a singly linked list. Hint: A linked list can be reversed either iteratively or recursively. Could you implement both? 解法一: class Solution { public: ListNode* reverseList(ListNode* head) { ListNode * pre = NULL;…

606. Construct String from Binary Tree [easy] You need to construct a string consists of parenthesis and integers from a binary tree with the preorder traversing way. The null node needs to be represented by empty parenthesis pair "()". And you…

189. Rotate Array[easy] Rotate an array of n elements to the right by k steps. For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4]. Note:Try to come up as many solutions as you can, there are at least 3 differen…

551. Student Attendance Record I[easy] You are given a string representing an attendance record for a student. The record only contains the following three characters: 'A' : Absent. 'L' : Late. 'P' : Present. A student could be rewarded if his attend…

383. Ransom Note[easy] Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constructed from the magazines ; otherwise, it will return fal…