96. Unique Binary Search Trees
Question Given n, how many structurally unique BST's (binary search trees) that store values 1 ... n? Example: Input: 3 Output: 5 Explanation: Given n = 3, there are a total of 5 unique…
92. Reverse Linked List II
Question Reverse a linked list from position m to n. Do it in one-pass. Note: 1 ≤ m ≤ n ≤ length of list. Example: Input: 1->2->3->4->5->NULL, m = 2 , n = 4 Output: 1->4->3->2->5->NULL Solution /** *…
226. Invert Binary Tree
Invert a binary tree. Example: Input: 4 / \ 2 7 / \ / \ 1 3 6 9 Output: 4 / \ 7 2 / \ / \ 9…
429. N-ary Tree Level Order Traversal
Question Given an n-ary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example, given a 3-ary tree: We should…
106. Construct Binary Tree from Inorder and Postorder Traversal
Questioin 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]…
105. Construct Binary Tree from Preorder and Inorder Traversal
Question 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]…
Leetcode 199. Binary Tree Right Side View
Question Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom. Example: Input: [1,2,3,null,5,null,4] Output:…
Leetcode 107. Binary Tree Level Order Traversal II
Question 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],…
Leetcode 617. Merge Two Binary Trees
Question Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are…
125. Valid Palindrome
Question Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. Note: For the purpose of this problem, we define empty string as valid palindrome.…