We are given a list schedule of employees, which represents the working time for each employee. Each employee has a list of non-overlapping Intervals, and these intervals are in sorted order. Return the list of finite intervals representing common, p…

There is a ball in a maze with empty spaces and walls. The ball can go through empty spaces by rolling up(u), down (d), left (l) or right (r), but it won't stop rolling until hitting a wall. When the ball stops, it could choose the next direction. Th…

A car travels from a starting position to a destination which is target miles east of the starting position. Along the way, there are gas stations.  Each station[i] represents a gas station that is station[i][0]miles east of the starting position, an…

Start from integer 1, remove any integer that contains 9 such as 9, 19, 29... So now, you will have a new integer sequence: 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, ... Given a positive integer n, you need to return the n-th integer after removing. Note that…

Given an array A (index starts at 1) consisting of N integers: A1, A2, ..., AN and an integer B. The integer B denotes that from any place (suppose the index is i) in the array A, you can jump to any one of the place in the array A indexed i+1, i+2,…

Given a list of words and two words word1 and word2, return the shortest distance between these two words in the list. word1 and word2 may be the same and they represent two individual words in the list. Example:Assume that words = ["practice",…

Design a class which receives a list of words in the constructor, and implements a method that takes two words word1 and word2 and return the shortest distance between these two words in the list. Your method will be called repeatedly many times with…

Given a sorted integer array nums, where the range of elements are in the inclusive range [lower, upper], return its missing ranges. example: Input: nums = [0, 1, 3, 50, 75], lower = 0 and upper = 99, Output: ["2", "4->49", "51…

There is a garden with N slots. In each slot, there is a flower. The N flowers will bloom one by one in Ndays. In each day, there will be exactly one flower blooming and it will be in the status of blooming since then. Given an array flowers consists…

Given strings S and T, find the minimum (contiguous) substring W of S, so that T is a subsequenceof W. If there is no such window in S that covers all characters in T, return the empty string "". If there are multiple such minimum-length windows…