题目链接 题目要求: 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 differ by more than 1. 这道题难度还好.具体程序(16ms)如下: /*…

leetcode面试准备:Implement Trie (Prefix Tree) 1 题目 Implement a trie withinsert, search, and startsWith methods. Note: You may assume that all inputs are consist of lowercase letters a-z. 2 思路 该题是实现trie树. Trie,又称单词查找树或键树,是一种树形结构.典型应用是用于统计和排序大量的字符串(但不仅限于字符…

leetcode面试准备:Lowest Common Ancestor of a Binary Search Tree & Binary Tree 1 题目 Binary Search Tree的LCA Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST. According to the definition of LCA on Wikiped…

Given a binary tree, find all leaves and then remove those leaves. Then repeat the previous steps until the tree is empty. Example:Given binary tree 1 / \ 2 3 / \ 4 5 Returns [4, 5, 3], [2], [1]. Explanation: 1. Remove the leaves [4, 5, 3] from the t…

LeetCode & tree & binary tree 树 & 二叉树 refs https://leetcode.com/problemset/all/?topicSlugs=tree https://leetcode.com/problems/merge-two-binary-trees/ https://leetcode.com/problems/maximum-depth-of-binary-tree/ https://leetcode.com/problemset/t…

动态树是一类要求维护森林的连通性的题的总称,这类问题要求维护某个点到根的某些数据,支持树的切分,合并,以及对子树的某些操作.其中解决这一问题的某些简化版(不包括对子树的操作)的基础数据结构就是LCT(link-cut tree). LCT的大体思想类似于树链剖分中的轻重链剖分(轻重链剖分请移步http://www.cnblogs.com/BLADEVIL/p/3479713.html),轻重链剖分是处理出重链来,由于重链的定义和树链剖分是处理静态树所限,重链不会变化,变化的只是重链上的边或点的权…

[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…

leetcode算法: Find Bottom Left Tree ValueGiven a binary tree, find the leftmost value in the last row of the tree.Example 1:Input: 2 / \ 1 3Output:1Example 2: Input: 1 / \ 2 3 / / \ 4 5 6 / 7Output:7Note: You may assume the tree (i.e., the given root n…

[BZOJ3080]Minimum Variance Spanning Tree/[BZOJ3754]Tree之最小方差树 题目大意: 给定一个\(n(n\le50)\)个点,\(m(m\le1000)\)条边的带权无向图,每条边的边权为\(w_i(w_i\le50)\).求最小方差生成树. 3080数据范围:\(n\le50,m\le1000,w_i\le50\): 3754数据范围:\(n\le100,m\le1000,w_i\le100\). 其中3754询问的是最小标准差. 思路: 由于…

[UOJ#388][UNR#3]配对树(线段树,dsu on tree) 题面 UOJ 题解 考虑一个固定区间怎么计算答案,把这些点搞下来建树,然后\(dp\),不难发现一个点如果子树内能够匹配的话就一定会匹配完,所以\(dp\)可以做到线性. 那么根据上面的\(dp\)方式,一条边会被匹配到,当且仅当把这条边删掉之后,两个连通块内分别有奇数个目标点.那么如果我们考虑枚举每一条边,然后把子树内的点给标记一下,于是变成了在原序列上求有多少个偶数区间满足有偶数个点被标记,这个问题可以做一个前缀和,把…