Provide Best Programming Tutorials

## 114. Flatten Binary Tree to Linked List

Question 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…

## 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],…

## 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.…

## Leetcode 234. Palindrome Linked List

Question Given a singly linked list, determine if it is a palindrome. Example 1: Input: 1->2 Output: false Example 2: Input: 1->2->2->1 Output: true Follow up: Could you do it…

## Leetcode 21. Merge Two Sorted Lists

Question Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. Example:…