## Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without repeating characters.

## Lowest Common Ancestor of a Binary Tree IV

Given the root of a binary tree and an array of TreeNode objects nodes, return the lowest common ancestor (LCA) of all the nodes in nodes.

## Lowest Common Ancestor of a Binary Tree

Medium Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.

## Implement Trie (Prefix Tree)

In computer science, a trie, also called digital tree or prefix tree, is a kind of search tree—an ordered tree data structure used to store a dynamic set or associative array where the keys are usually strings.

## Container With Most Water

Given n non-negative integers a1, a2, …, an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of the line i is at (i, ai) and (i, 0). Find two lines, which, together with the x-axis forms a container, such that the container contains the most water.

## Binary Tree Maximum Path Sum

A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence at most once. Note that the path does not need to pass through the root.

## Longest Increasing Path in a Matrix

Given an m x n integers matrix, return the length of the longest increasing path in matrix.

## Boundary of Binary Tree

Given a binary tree, print boundary nodes of the binary tree Anti-Clockwise starting from the root. The boundary includes left boundary, leaves, and right boundary in order without duplicate nodes.

## Serialize and Deserialize Binary Tree

HARD Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or […]

## Word Search

Medium Given an m x n board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cells, where “adjacent” cells are horizontally […]