题目链接 描述 Little Valentine liked playing with binary trees very much. Her favorite game was constructing randomly looking binary trees with capital letters in the nodes.  This is an example of one of her creations:  D / \ / \ B E / \ \ / \ \ A C G / /…

判断一棵树是否自对称 可以回忆我们做过的Leetcode 100 Same Tree 二叉树和Leetcode 226 Invert Binary Tree 二叉树 先可以将左子树进行Invert Binary Tree,然后用Same Tree比较左右子树 而我的做法是改下Same Tree的函数,改动的是第27行 /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left;…

判断一棵树是否是平衡树,即左右子树的深度相差不超过1. 我们可以回顾下depth函数其实是Leetcode 104 Maximum Depth of Binary Tree 二叉树 /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL…

4.7 Design an algorithm and write code to find the first common ancestor of two nodes in a binary tree. Avoid storing additional nodes in a data structure. NOTE: This is not necessarily a binary search tree. LeetCode上的原题,请参见我之前的博客Lowest Common Ancest…

[Leetcode] Maximum and Minimum Depth of Binary Tree 二叉树的最小最大深度 (最小有3种解法) 描述 解析 递归深度优先搜索 当求最大深度时,我们只要在左右子树中取较大的就行了. 然而最小深度时,如果左右子树中有一个为空会返回0,这时我们是不能算做有效深度的. 所以分成了三种情况,左子树为空,右子树为空,左右子树都不为空.当然,如果左右子树都为空的话,就会返回1. 广度优先搜索(类似层序遍历的思想) 递归解法本质是深度优先搜索,但因为我们是求最小…

UVA.548 Tree(二叉树 DFS) 题意分析 给出一棵树的中序遍历和后序遍历,从所有叶子节点中找到一个使得其到根节点的权值最小.若有多个,输出叶子节点本身权值小的那个节点. 先递归建树,然后DFS求解. 代码总览 #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <string> #include <sstre…

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. 给一个二叉树,找出它的最小深度.最小深度是从根节点向下到最近的叶节点的最短路径,就是最短路径的节点个数. 解法1:DFS 解法2: BFS Java: DFS, Time Comp…

Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root. Example:Given a binary t…

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another comput…

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w…