Robina Li

Difficulty: Medium Category: Tree, DFS, BFS, Graph

Difficulty: Hard Category: Stack, Monotonic Stack

Difficulty: Medium Category: DFS, Graph, Matrix

Difficulty: Medium Category: Run-Length Encoding, Two Pointers, Array Processing

Given two sparse vectors, compute their dot product.

You are given two integer arrays nums1 and nums2. You are tasked to implement a data structure that supports the following operations:

Given the root of a binary tree and an integer targetSum, return the number of paths where the sum of the values along the path equals targetSum.

Given an encoded string, return its decoded string.

There is an m x n rectangular island that borders both the Pacific Ocean and the Atlantic Ocean. The Pacific Ocean touches the island’s left and top edges, and the...

You are given an array of people, people, which are the attributes of some people in a queue (not necessarily in order). Each people[i] = [hi, ki] represents the ith...