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You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition: struct Node { int val; Node *left; Node *ri...

Given a binary tree, flatten it to a linked list in-place. For example, given the following tree: 1 / 2 5 / \ 3 4 6 The flattened tree should look like: 1 2 3 4 5 6 知识点 stack 先进先出 pop ...

Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum. Note: A leaf is a node with no children. Example: Given the below binary tree and sum = 22, 5 ...

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. Note: A leaf is a node with no children....

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 left and right subtrees of every node differ in heigh...

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is defined as a binary tree in which the d...

二分查找中的问题 循环条件为什么不是 (l<r) 第一，如果数组长度为1的话，不管查找什么都会恒定的返回-1，这显然是错的。 第二，当l + 1 = r的时候，mid=l，如果此时A[mid]小于target执行l=mid+1=r，再次循环时候while条件不满足，将退出循环，但是A[right]可能==target。考虑[3,5] k=5的情况，这时候会返 nick大神讲解 看了视频发现了...

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 retu...

Binary Tree Level Order Traversal II Easy 1039 186 Add to List Share Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (ie, from left to right, level by level fro...

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,...

Given a binary tree, return the inorder traversal of its nodes’ values. Example: Input: [1,null,2,3] 1 2 / 3 Output: [1,3,2] Follow up: Recursive solution is trivial, could you do it iteratively? 题意很...