shadowkun的博客

You are given aperfect binary treewhereall 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; N...

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

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 andsum = 22,...

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.Note:A leaf is a node with no children.Example:...

Given an array 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 depth of the...

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, giveninorder =[9,3,15,20,7]postorder = [9...

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, givenpreorder =[3,9,20,15,7]inorder = [9,3...

Given a binary tree, return thezigzag level ordertraversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between).For example:Given binary tr...

Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains only nodes with keysless thanthe node's key. The ...

Givenn, how many structurally uniqueBST's(binary search trees) that store values 1 ...n?Example:Input: 3Output: 5Explanation:Given n = 3, there are a total of 5 unique BST's:1 3...

Given a binary tree, return thelevel ordertraversal 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...

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree[1,2,2,3,4,4,3]is symmetric: 1 / \ 2 2/ \ / \3 4 4 3...