Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new length.

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.An input string is valid if:Open brackets must be closed by the same type of brackets.Open brackets must be closed in the correct order.Note that an empty string is also considere...

Write a function to find the longest common prefix string amongst an array of strings.

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Given an unsorted integer array, find the smallest missing positive integer.

Given a 32-bit signed integer, reverse digits of an integer. Example 1:Input: 123Output: 321 Example 2:Input: -123Output: -321 Example 3:Input: 120Output: 21 Note:Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For...

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

Given an array nums of n integers, are there elements a, b, c in nums such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Given n non-negative integers a1, a2, ..., an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most w...

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that "all houses in this place forms a binary tree". It will automatic...

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, adjacent houses have security system connected and it wi...

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and it will automatically contact the police if two adjacent hou...

Design a data structure that supports the following two operations:void addWord(word)bool search(word)search(word) can search a literal word or a regular expression string containing only letters a-z or .. A . means it can represent any one letter.

In a country popular for train travel, you have planned some train travelling one year in advance. The days of the year that you will travel is given as an array days. Each day is an integer from 1 to 365.

In a N x N grid composed of 1 x 1 squares, each 1 x 1 square consists of a /, , or blank space. These characters divide the square into contiguous regions.

Given a binary tree, find the leftmost value in the last row of the tree.

Given a matrix consists of 0 and 1, find the distance of the nearest 0 for each cell.

There are a total of n courses you have to take, labeled from 0 to n-1.

There are a total of n courses you have to take, labeled from 0 to n-1.

Given a non-empty array of integers, every element appears three times except for one, which appears exactly once. Find that single one.

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 appear only once.

All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA.

Note:You may assume that all inputs are consist of lowercase letters a-z.All inputs are guaranteed to be non-empty strings.

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.

Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn't one, return 0 instead.

Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive.