For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

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 BFS 相似题目 参考资料 日期 题目地址:https://leetcode.com/problems/minimum-height-trees/description/ 题目描述 For a undirected graph with tree characteristics, we can choose any node as the root.…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

原题链接在这里:https://leetcode.com/problems/minimum-height-trees/ 题目: For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height a…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

For an undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, writ…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

2018-09-24 12:01:38 问题描述: 问题求解: 毫无疑问的一条非常好的题目,采用的解法是逆向的BFS,也就是从叶子节点开始遍历,逐步向中心靠拢,最终留下的叶子节点就是答案. public List<Integer> findMinHeightTrees(int n, int[][] edges) { // tricks :使用Collections.singletonList(0)可以直接返回单个值的List if (n == 1) return Collections.sin…

2018-09-24 12:01:38 问题描述: 对于一个具有树特征的无向图,我们可选择任何一个节点作为根.图因此可以成为树,在所有可能的树中,具有最小高度的树被称为最小高度树.给出这样的一个图,写出一个函数找到所有的最小高度树并返回他们的根节点. 格式 该图包含 n 个节点,标记为 0 到 n - 1.给定数字 n 和一个无向边 edges 列表(每一个边都是一对标签). 你可以假设没有重复的边会出现在 edges 中.由于所有的边都是无向边, [0, 1]和 [1, 0] 是相同的,因此不…

LeetCode:Unique Binary Search Trees Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 分析:依次把每个节点作…

[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 Find Minimum in Rotated Sorted Array 题目大意: 对一个有序数组翻转, 就是随机取前K个数,移动到数组的后面,然后让你找出最小的那个数.注意,K有可能是0,也就是没有翻转. 毫无疑问,遍历一次肯定能够找到,但这样时间复杂度是O(n).假设你在面试的时候遇到这种问题,你这样回答面试官肯定不会惬意的.我们接下来讨论有没有什么更快的方法.O(nlogn)?? 我还是把O(N)的代码贴出来,不知道为什么leetcode上竟然不超时. //O(n) c…

Leetcode 931. Minimum falling path sum 最小下降路径和(动态规划) 题目描述 已知一个正方形二维数组A,我们想找到一条最小下降路径的和 所谓下降路径是指,从一行到下一行,只能选择间距不超过1的列(也就是说第一行的第一列,只能选择第二行的第一列和第二列:第二行的第二列,只能选择第三行的第一列第二列第三列),最小下降路径就是这个路径的和最小 测试样例 Input: [[1,2,3],[4,5,6],[7,8,9]] Output: 12 Explanation:…

Given strings S and T, find the minimum (contiguous) substring W of S, so that T is a subsequenceof W. If there is no such window in S that covers all characters in T, return the empty string "". If there are multiple such minimum-length windows…

Simple data structure but not that easy to figure out.. MHT -> balanced tree.https://leetcode.com/problems/minimum-height-trees/ Lesson learnt: Focus on problem itself. Play with it. Do NOT jam your brain with knowledge! class Solution { public: vect…

You are asked to cut off trees in a forest for a golf event. The forest is represented as a non-negative 2D map, in this map: 0 represents the obstacle can't be reached. 1 represents the ground can be walked through. The place with number bigger than…

原题链接在这里:https://leetcode.com/problems/cut-off-trees-for-golf-event/description/ 题目: You are asked to cut off trees in a forest for a golf event. The forest is represented as a non-negative 2D map, in this map: 0 represents the obstacle can't be reach…

You are asked to cut off trees in a forest for a golf event. The forest is represented as a non-negative 2D map, in this map: 0 represents the obstacle can't be reached. 1 represents the ground can be walked through. The place with number bigger than…

    题目URL:https://leetcode.com/problems/minimum-depth-of-binary-tree/ 111. Minimum Depth of Binary Tree My Submissions Question Total Accepted: 94580 Total Submissions: 312802 Difficulty: Easy Given a binary tree, find its minimum depth. The minimum…

原题链接在这里:https://leetcode.com/problems/minimum-cost-tree-from-leaf-values/ 题目: Given an array arr of positive integers, consider all binary trees such that: Each node has either 0 or 2 children; The values of arr correspond to the values of each leaf …

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…

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 排序比较 日期 题目地址:https://leetcode.com/problems/height-checker/ 题目描述 Students are asked to stand in non-decreasing order of heights for an annual photo. Return the minimum number of…

Follow up for "Find Minimum in Rotated Sorted Array":What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might be…

Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). Find the minimum element. You may assume no duplicate exists in the array. 这道寻找旋转有序数组的最小值肯定不能通过直接遍历整个数组来寻找,这个方法过于简单粗暴,这样的话,旋不…

Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 这道题实际上是Catalan Number卡塔兰数的一个例子,如果对卡塔兰数不熟悉的童鞋可能真…