Robina Li

You are given an integer array nums and you have to return a new array counts. The array counts has the property where counts[i] is the number of smaller elements...

LCR 113. Course Schedule II

A tree is an undirected graph in which any two vertices are connected by exactly one path. In other words, any connected graph without simple cycles is a tree.

There is a new alien language that uses the English alphabet. However, the order among the letters is unknown to you.

Design a queue that supports push and pop operations in the front, middle, and back.

Given an m x n grid of characters board and a string word, return true if word exists in the grid.

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other.

Given two strings s and t, return true if they are equal when both are typed into empty text editors. '#' means a backspace character.

Given a list of accounts where each element accounts[i] is a list of strings, where the first element accounts[i][0] is a name, and the rest of the elements are emails...