Definition of a complete binary tree from Wikipedia:In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2^h nodes inclusive at the last level h.

Find the total area covered by two rectilinear rectangles in a 2D plane.

Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.

Given an array of integers, 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.

Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes.

You have an array of logs. Each log is a space delimited string of words.

Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histogram.

Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. Assume that there is only one duplicate number, find the duplicate one.

Compare two version numbers version1 and version2.If version1 > version2 return 1; if version1 < version2 return -1;otherwise return 0.

Given a binary tree, return the values of its boundary in anti-clockwise direction starting from root. Boundary includes left boundary, leaves, and right boundary in order without duplicate nodes.

Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

Suppose you have a long flowerbed in which some of the plots are planted and some are not. However, flowers cannot be planted in adjacent plots - they would compete for water and both would die.

The transpose of a matrix is the matrix flipped over it's main diagonal, switching the row and column indices of the matrix.

Given a non-empty, singly linked list with head node head, return a middle node of linked list.

Winter is coming! Your first job during the contest is to design a standard heater with fixed warm radius to warm all the houses.

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 not.

Given an array A of non-negative integers, return an array consisting of all the even elements of A, followed by all the odd elements of A.

Implement function ToLowerCase() that has a string parameter str, and returns the same string in lowercase.

Given a linked list, rotate the list to the right by k places, where k is non-negative.

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

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.

Given a string, we can "shift" each of its letter to its successive letter, for example: "abc" -> "bcd". We can keep "shifting" which forms the sequence:

Given a list of airline tickets represented by pairs of departure and arrival airports [from, to], reconstruct the itinerary in order. All of the tickets belong to a man who departs from JFK. Thus, the itinerary must begin with JFK.

In a N x N grid representing a field of cherries, each cell is one of three possible integers.

Given an m x n matrix of non-negative integers representing the height of each unit cell in a continent, the "Pacific ocean" touches the left and top edges of the matrix and the "Atlantic ocean" touches the right and bottom edges.

Given a nested list of integers, return the sum of all integers in the list weighted by their depth.

Given a string S, check if the letters can be rearranged so that two characters that are adjacent to each other are not the same.

Given a string S and a string T, count the number of distinct subsequences of S which equals T.

The Employee table holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id.

Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible.