problem 993. Cousins in Binary Tree 参考 1. Leetcode_easy_993. Cousins in Binary Tree; 完…

题目如下: In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1. Two nodes of a binary tree are cousins if they have the same depth, but have different parents. We are given the root of a binary tree with uniqu…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 DFS BFS 日期 题目地址:https://leetcode.com/problems/cousins-in-binary-tree/ 题目描述 In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1. Tw…

problem 543. Diameter of Binary Tree 题意: 转换一种角度来看,是不是其实就是根结点1的左右两个子树的深度之和呢.那么我们只要对每一个结点求出其左右子树深度之和,这个值作为一个候选值,然后再对左右子结点分别调用求直径对递归函数,这三个值相互比较,取最大的值更新结果res,因为直径不一定会经过根结点,所以才要对左右子结点再分别算一次.为了减少重复计算,我们用哈希表建立每个结点和其深度之间的映射,这样某个结点的深度之前计算过了,就不用再次计算了. solution…

[LeetCode]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. 递归和非递归,此提比较简单.广度优先遍历即可.关键之处就在于如何保持访问深度. 下面是4种代码: im…

[CF438E]The Child and Binary Tree(多项式运算,生成函数) 题面 有一个大小为\(n\)的集合\(S\) 问所有点权都在集合中,并且点权之和分别为\([0,m]\)的二叉树的个数. \(n,m<=10^5\) 题解 设\(f(i)\)表示点权和为\(i\)的二叉树个数,\(c(i)\)是集合中数的生成函数,那么我们可以得到 \[f(n)=\sum_{i=1}^{n}c(i)\sum_{j=0}^{n-i}f(j)f(n-i-j)\] 显然有\(f(0)=1\) 构…

993. Cousins in Binary Tree In a binary tree, the root node is at depth 0, and children of each depth knode are at depth k+1. Two nodes of a binary tree are cousins if they have the same depth, but have different parents. We are given the root of a b…

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. 递归的解题思路: 递归当前结点,分一下四种情况考虑:①结点为空时返回0:②结点没有右子树时,返回左子树最小值+1:③结点没有左子树时,返回右子树最小值+1:④当结点双子齐全时,返回…

题目要求 In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1. Two nodes of a binary tree are cousins if they have the same depth, but have different parents. We are given the root of a binary tree with unique…

题目简述: 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. 解题思路: # Definition for a binary tree node # class TreeNode: # def __init__(self, x):…