Given the root of a binary tree with N nodes, each node in the tree has node.val coins, and there are N coins total. In one move, we may choose two adjacent nodes and move one coin from one node to another.  (The move may be from parent to child, or…

原题链接在这里:https://leetcode.com/problems/distribute-coins-in-binary-tree/ 题目: Given the root of a binary tree with N nodes, each node in the tree has node.val coins, and there are N coins total. In one move, we may choose two adjacent nodes and move one…

题目如下: Given the root of a binary tree with N nodes, each node in the tree has node.val coins, and there are Ncoins total. In one move, we may choose two adjacent nodes and move one coin from one node to another.  (The move may be from parent to child…

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 递归 日期 题目地址:https://leetcode.com/problems/distribute-coins-in-binary-tree/ 题目描述 Given the root of a binary tree with N nodes, each node in the tree has node.val coins, and there…

Given the root of a binary tree with N nodes, each node in the tree has node.val coins, and there are N coins total. In one move, we may choose two adjacent nodes and move one coin from one node to another.  (The move may be from parent to child, or…

问题 给定一个二叉树的root节点,二叉树中每个节点有node.val个coins,一种有N coins. 现在要求移动节点中的coins 使得二叉树最终每个节点的coins value都为1.每次移动,我们只能向相邻接点移动,也就是说coins 只能向父节点或者子节点移动,那么求最终需要移动多少步. Leetcode原题链接: https://leetcode.com/problems/distribute-coins-in-binary-tree/ 分析 如果叶子节点有0个coins,那么我…

2019-03-27 15:53:38 问题描述: 问题求解: 很有意思的题目.充分体现了二叉树的自底向上的递归思路. 自底向上进行运算,对于最底层的二叉子树,我们需要计算每个节点向其parent传送多余的硬币数量,不论正负,都是需要占用move数量的.自此递归的进行计数即可. public int distributeCoins(TreeNode root) { int[] res = new int[1]; helper(root, res); return res[0]; } privat…

问题: Serialize and Deserialize Binary Tree 描述: 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 rec…

Given a binary tree, write a function to get the maximum width of the given tree. The width of a tree is the maximum width among all levels. The binary tree has the same structure as a full binary tree, but some nodes are null. The width of one level…

Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. Note: A leaf is a node with no children. Example: Given binary tree [3,9,20,null,null,15,7…

1 题目 Invert a binary tree. 4 / \ 2 7 / \ / \ 1 3 6 9 to 4 / \ 7 2 / \ / \ 9 6 3 1 接口: public TreeNode invertTree(TreeNode root) 2 思路 反转一颗二叉树. 可以用递归和非递归两种方法来解. 递归的方法,写法非常简洁,五行代码搞定,交换当前左右节点,并直接调用递归即可. 非递归的方法,参考树的层序遍历,借助Queue来辅助,先把根节点排入队列中,然后从队中取出来,交换其左…

Given a binary tree, we install cameras on the nodes of the tree. Each camera at a node can monitor its parent, itself, and its immediate children. Calculate the minimum number of cameras needed to monitor all nodes of the tree. Example 1: Input: [0,…

题目描述 144. Binary Tree Preorder Traversal 94. Binary Tree Inorder Traversal 145. Binary Tree Postorder Traversal 前序排列 :根-左-右 中序排列: 左-根-右 后序排列:左-右-根 参考答案 // PreOrder /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *le…

Given a binary tree, return the vertical order traversal of its nodes values. For each node at position (X, Y), its left and right children respectively will be at positions (X-1, Y-1) and (X+1, Y-1). Running a vertical line from X = -infinity to X =…

问题描述 Given a binary tree, return the inorder traversal of its nodes' values. (左 - 根 - 右) Example: Input: [1,null,2,3] 1 \ 2 / 3 Output: [1,3,2] Follow up: Recursive solution is trivial, could you do it iteratively? 参考答案 /** * Definition for a binary…

Given a binary tree with N nodes, each node has a different value from {1, ..., N}. A node in this binary tree can be flipped by swapping the left child and the right child of that node. Consider the sequence of N values reported by a preorder traver…

Print a binary tree in an m*n 2D string array following these rules: The row number m should be equal to the height of the given binary tree. The column number n should always be an odd number. The root node's value (in string format) should be put i…

A binary tree is univalued if every node in the tree has the same value. Return true if and only if the given tree is univalued. 太简单了,签到题.…

Return any binary tree that matches the given preorder and postorder traversals. Values in the traversals pre and post are distinct positive integers. Example 1: Input: pre = [1,2,4,5,3,6,7], post = [4,5,2,6,7,3,1] Output: [1,2,3,4,5,6,7] Note: 1 <=…

Design an algorithm to encode an N-ary tree into a binary tree and decode the binary tree to get the original N-ary tree. An N-ary tree is a rooted tree in which each node has no more than N children. Similarly, a binary tree is a rooted tree in whic…

We are given a binary tree (with root node root), a target node, and an integer value K. Return a list of the values of all nodes that have a distance K from the target node.  The answer can be returned in any order. Example 1: Input: root = [3,5,1,6…

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 longestpath between any two nodes in a tree. This path may or may not pass through the root. Example:Given a binary tr…

Given a binary tree, return the vertical order traversal of its nodes' values. (ie, from top to bottom, column by column). If two nodes are in the same row and column, the order should be from left to right. Examples 1: Input: [3,9,20,null,null,15,7]…

Given a binary tree where all the right nodes are either leaf nodes with a sibling (a left node that shares the same parent node) or empty, flip it upside down and turn it into a tree where the original right nodes turned into left leaf nodes. Return…

Given inorder and postorder traversal of a tree, construct the binary tree. Note:You may assume that duplicates do not exist in the tree. For example, given inorder = [9,3,15,20,7] postorder = [9,15,7,20,3] Return the following binary tree: 3 / \ 9 2…

Given preorder and inorder traversal of a tree, construct the binary tree. Note:You may assume that duplicates do not exist in the tree. For example, given preorder = [3,9,20,15,7] inorder = [9,3,15,20,7] Return the following binary tree: 3 / \ 9 20…

Given a binary tree, find the length of the longest consecutive sequence path. The path refers to any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The longest consecutive path need to be from p…

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,null,null,15,7], 3 / \ 9 20 / \ 15 7 return its level order traversal as: [ [3], [9,20], [15,7…

Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). For example:Given binary tree [3,9,20,null,null,15,7], 3 / \ 9 20 / \ 15 7 return its bottom-up level or…

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. Example 1: Given the following tre…