Given an array of numbers nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appea...

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb...

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 tha...

You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k.

Given n balloons, indexed from 0 to n-1. Each balloon is painted with a number on it represented by array nums. You are asked to burst all the balloons. If the ...

Find the sum of all left leaves in a given binary tree.

Find the nth digit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, …

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

4SumDesicriptionGiven an array S of n integers, are there elements a, b, c, and d in S such that a

3SumDesicriptionGiven an array S of n integers, are there elements a, b, c in S such that a + b +