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. 二叉树相同:一.结构相同:二.对应节点上的值相同. 思路:层次遍历,维护两个队列,判断对应节点的值是否相等.值得注意的有:一.节点均…

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. 判断两棵树是否相同和之前的判断两棵树是否对称都是一样的原理,利用深度优先搜索DFS来递归.代码如下: 解法一: class Solu…

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree is symmetric: 1 / \ 2 2 / \ / \ 3 4 4 3 But the following is not: 1 / \ 2 2 \ \ 3 3 Note:Bonus points if you could solve it b…

  思路: 主要判断左子树与右子树. 在判断左时,循环下去肯定会到达叶子结点中最左边的结点与最右边的结点比较. 到了这一步因为他们都没有左(右)子树了,所以得开始判断这两个结点的右(左)子树了. 当某个结点对称了,它的左子树也对称了,右子树也对称了,那才是真的对称了. C++ /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode…

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree is symmetric: 1 / \ 2 2 / \ / \ 3 4 4 3 But the following is not: 1 / \ 2 2 \ \ 3 3 Note:Bonus points if you could solve it b…

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree [1,2,2,3,4,4,3] is symmetric: 1 / \ 2 2 / \ / \ 3 4 4 3 But the following [1,2,2,null,3,null,3] is not: / \ \ \ Note:Bonus po…

LeetCode: Binary Tree Traversal 题目:树的先序和后序. 后序地址:https://oj.leetcode.com/problems/binary-tree-postorder-traversal/ 先序地址:https://oj.leetcode.com/problems/binary-tree-preorder-traversal/ 后序算法:利用栈的非递归算法.初始时,先从根节点一直往左走到底,并把相应的元素进栈:在循环里每次都取出栈顶元素,如果该栈顶元素的右…

题意:判断有向图是否为树 链接:点我 这题用并查集判断连通,连通后有且仅有1个入度为0,其余入度为1,就是树了 #include<cstdio> #include<iostream> #include<algorithm> #include<cstring> #include<cmath> #include<queue> #include<map> using namespace std; #define MOD 1000…

[js]Leetcode每日一题-叶子相似的树 [题目描述] 请考虑一棵二叉树上所有的叶子,这些叶子的值按从左到右的顺序排列形成一个 叶值序列 . 举个例子,如上图所示,给定一棵叶值序列为 (6, 7, 4, 9, 8) 的树. 如果有两棵二叉树的叶值序列是相同,那么我们就认为它们是 叶相似 的. 如果给定的两个根结点分别为 root1 和 root2 的树是叶相似的,则返回 true:否则返回 false . 示例 1: 输入:root1 = [3,5,1,6,2,9,8,null,null,…

LeetCode: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). For example:Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20 / \ 15 7 return its level ord…