原题地址:https://oj.leetcode.com/problems/rotate-list/ 题意: Given a list, rotate the list to the right by k places, where k is non-negative. For example:Given 1->2->3->4->5->NULL and k = 2,return 4->5->1->2->3->NULL. 解题思路:循环右移一条链表…

原题地址:https://oj.leetcode.com/problems/rotate-image/ 题意: You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Follow up:Could you do this in-place? 解题思路:先将矩阵转置,然后将矩阵的每一行翻转,就可以得到所要求的矩阵了. 代码: class Solution…

STL中的list就是一双向链表,可高效地进行插入删除元素. List 是 C++标准程式库 中的一个 类 ,可以简单视之为双向 连结串行 ,以线性列的方式管理物件集合.list 的特色是在集合的任何位置增加或删除元素都很快,但是不支持随机存取.list 是 C++标准程式库 提供的众多容器(container)之一,除此之外还有 vector .set.map.…等等.list 以模板方式实现(即泛型),可以处理任意型别的变量,包括使用者自定义的资料型态,例如:它可以是一个放置整数(int)型…

题目来源 https://leetcode.com/problems/rotate-list/ Given a list, rotate the list to the right by k places, where k is non-negative. For example:Given 1->2->3->4->5->NULL and k = 2,return 4->5->1->2->3->NULL. 题意分析 Input:a list of…

题目来源 https://leetcode.com/problems/rotate-image/ You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Follow up:Could you do this in-place? 题意分析 Input:a matrix represented with list[list[]] Output:a matr…

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 different ways to solve this pro…

Given a list, rotate the list to the right by k places, where k is non-negative. For example:Given 1->2->3->4->5->NULL and k = 2,return 4->5->1->2->3->NULL. 这道旋转链表的题和之前那道Rotate Array 旋转数组 很类似,但是比那道要难一些,因为链表的值不能通过下表来访问,只能一个一个的…

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Follow up:Could you do this in-place? 在计算机图像处理里,旋转图片是很常见的,由于图片的本质是二维数组,所以也就变成了对数组的操作处理,翻转的本质就是某个位置上数移动到另一个位置上,比如用一个简单的例子来分析: 1  2  3 7  4  1 4  5  6 -…

题目来源 https://leetcode.com/problems/valid-palindrome/ Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a plan, a canal: Panama" is a palindrome."race a car"…

题目来源 https://leetcode.com/problems/triangle/ Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below. For example, given the following triangle [ [], [,4], [6,,7], [4,,8,3] ] The min…

题目来源 https://leetcode.com/problems/pascals-triangle-ii/ Given an index k, return the kth row of the Pascal's triangle. For example, given k = 3,Return [1,3,3,1]. 题意分析 Input:integer Output:kth row of the Pascal's triangle Conditions:只返回第n行 题目思路 同118,不…

题目来源 https://leetcode.com/problems/pascals-triangle/ Given numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5,Return [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ] 题意分析 Input:integer Output:帕斯卡三角 Conditions:帕斯卡三…

题目来源 https://leetcode.com/problems/populating-next-right-pointers-in-each-node/ Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If th…

题目来源 https://leetcode.com/problems/flatten-binary-tree-to-linked-list/ Given a binary tree, flatten it to a linked list in-place. 题意分析 Input: binary tree Output: flattened tree Conditions:将一个二叉树压平为一个flatten 树,也就是一条斜线 题目思路 先将左右子树压平,然后将左子树嵌入到本节点与右子树之间.…

题目来源 https://leetcode.com/problems/path-sum-ii/ Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. 题意分析 Input: a binary tree, sum Output: list of list. Conditions: 给定一个二叉树,将所有root-leaf的路径值和等于sum的路径返…

题目来源 https://leetcode.com/problems/path-sum/ Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. 题意分析 Input: a binary tree, sum Output: True or False Con…

题目来源 https://leetcode.com/problems/minimum-depth-of-binary-tree/ Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. 题意分析 Input: a binary tree…

题目来源 https://leetcode.com/problems/balanced-binary-tree/ Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never d…

题目来源 https://leetcode.com/problems/binary-tree-level-order-traversal-ii/ Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). 题意分析 Input: binary tree Output:…

题目来源 https://leetcode.com/problems/maximum-depth-of-binary-tree/ Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. 题意分析 Input: tree Output:…

题目来源 https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/ Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). 题意分…

题目来源 https://leetcode.com/problems/binary-tree-level-order-traversal/ Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). 题意分析 Input: 一个二叉树 Output:一个每层数值组合的list Conditions:层次遍历 题目思路 采用…

题目来源 https://leetcode.com/problems/symmetric-tree/ Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). 题意分析 Input:一个二叉树 Output:True or False Conditions: 判断一个二叉树是不是对称的 题目思路 一一对应判断值是否相等,注意要清楚谁对应谁. AC代码(Python)…

题目来源 https://leetcode.com/problems/same-tree/ Given two binary trees, write a function to check if they are equal or not. Two binary trees are considered equal if they are structurally identical and the nodes have the same value. 题意分析 Input: twon bin…

题目来源 https://leetcode.com/problems/validate-binary-search-tree/ Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node'…

题目来源 https://leetcode.com/problems/binary-tree-inorder-traversal/ iven a binary tree, return the inorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,3,2]. 题意分析 Input:tree Output: inorder traversal Cond…

题目来源 https://leetcode.com/problems/restore-ip-addresses/ Given a string containing only digits, restore it by returning all possible valid IP address combinations. For example:Given "25525511135", return ["255.255.11.135", "255.25…

题目来源 https://leetcode.com/problems/reverse-linked-list-ii/ Reverse a linked list from position m to n. Do it in-place and in one-pass. For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4, return 1->4->3->2->5->NULL. Note:G…

题目来源 https://leetcode.com/problems/decode-ways/ A message containing letters from A-Z is being encoded to numbers using the following mapping: 'A' -> 1 'B' -> 2 ... 'Z' -> 26 Given an encoded message containing digits, determine the total number…

题目来源 https://leetcode.com/problems/gray-code/ The gray code is a binary numeral system where two successive values differ in only one bit. Given a non-negative integer n representing the total number of bits in the code, print the sequence of gray co…