Description: Suppose that all the keys in a binary tree are distinct positive integers. Given the postorder and inorder traversal sequences, a binary tree can be uniquely determined. Now given a sequence of statements about the structure of the resul…

problem description: 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. problem analysis: 第一步,设计演算法:遍历一棵树的方法有两种,BFS and DFS,思考了下,BFS是一圈一圈的扩张出…

Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For example:Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20 / \ 15 7 return its…

Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20 / \ 15 7 return [ [3], [9,20], [15,7] ] For the problem given I decided to use BFS,…

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. BFS碰到一个叶子结点就可以了. class Solution { public: int minDepth(TreeNo…

https://leetcode.com/contest/weekly-contest-79/problems/binary-tree-pruning/ -- 814 from leetcode tree traverse (post traverse) left right and root the model void traverse(node){ if(node.left!=null) traverse(node.left); if(node.right!=null) traverse(…

https://leetcode.com/problems/complete-binary-tree-inserter/ 给出树节点的定义和完全二叉树插入器类的定义,为这个类补全功能.完全二叉树的定义为:这颗二叉树除最后一层外左右层的节点都是满的(对于第i层有2^(i-1)个节点),最后一层节点都出现在尽量靠左的位置. /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left;…

Binary Tree : It is a tree data structure in which each node has at most two children. As such there is no relation between a parent and its left and right descendants. Hence they are unordered. Binary Search Tree : These are ordered binary trees wit…

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 non-empty binary tree, return the average value of the nodes on each level in the form of an array. Example 1: Input: 3 / \ 9 20 / \ 15 7 Output: [3, 14.5, 11] Explanation: The average value of nodes on level 0 is 3, on level 1 is 14.5, and o…