Follow up for “Remove Duplicates”: What if duplicates are allowed at most twice?For example, Given sorted array A = [1,1,1,2,2,3],Your function should return length = 5, and A is now [1,1,2,2,3].[cod

Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue.Here, we will use the integers 0, 1,

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Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is given below. Input:Digit string “23”

Given an unsorted integer array, find the first missing positive integer.For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2.Your algorithm should run in O(n) time and uses constant space.[c

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.You may assume no duplicates in the array.Here

Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm’s runtime complexity must be in the order of O(log n).If the target is not found in the ar

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:Integers in each row are sorted from left to right. The first integer of each row is

subsets Given a set of distinct integers, S, return all possible subsets.Note: Elements in a subset must be in non-descending order. The solution set must not contain duplicate subsets. For example,

candyThere are N children standing in a line. Each child is assigned a rating value. You are giving candies to these children subjected to the following requirements: Each child must have at least o

Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). You are given a target value to search. If found in the array return its in

Given numRows, generate the first numRows of Pascal’s triangle. For example, given numRows = 5, Return[ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1]][code]public class Solution { p

Find the contiguous subarray within an array (containing at least one number) which has the largest product.For example, given the array [2,3,-2,4], the contiguous subarray [2,3] has the largest produ

A peak element is an element that is greater than its neighbors.Given an input array where num[i] ≠ num[i+1], find a peak element and return its index.The array may contain multiple peaks, in that case

Given a collection of intervals, merge all overlapping intervals.For example, Given [1,3],[2,6],[8,10],[15,18], return [1,6],[8,10],[15,18].题中给出的intervals实际上是已经按start排好序的, otherwise，需要implements

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times. You may assume that the array is non-empty and the majority element alway

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.算法： 1. if height[i]>=stack.peek(), push 2.

Given a sorted linked list, delete all duplicates such that each element appear only once.For example, Given 1->1->2, return 1->2. Given 1->1->2->3->3, return 1->2->3.**[code]**Remove Duplicates from

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.For example, Given 1->2->3->3->4->4->5, return 1->2->5. Given 1->1->1->2

Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.Do not allocate extra space for another array, you must do this in place with cons

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lowest possible orde

Two SumGiven an array of integers, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers such that they add up to the target, w

Given an array and a value, remove all instances of that value in place and return the new length.The order of elements can be changed. It doesn’t matter what you leave beyond the new length.[code]publ

Given an unsorted array of integers, find the length of the longest consecutive elements sequence.For example, Given [100, 4, 200, 1, 3, 2], The longest consecutive elements sequence is [1, 2, 3, 4].

There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).[code]public class Solution { publ

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Follow up: Could you do this in-place?[code]public class Solution { public void rotate(int[][]

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.public class Solution { public void setZeroes(int[][] matrix) { if(matrix==null)return;

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining. For example, Given [0,1,0,2,1,0,1,3,2,1,2,1]

Valid sudokuDetermine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules. The Sudoku board could be partially filled, where empty cells are filled with the character ‘.’.public class Solut

The gray code is a binary numeral system where two successive values differ in only one bit.Given a non-negative integer n representing the total number of bits in the code, print the sequence of gray

public class Solution { public int maximalRectangle(char[][] matrix) { if(matrix==null || matrix.length==0 || matrix[0].length==0)return 0; int m=matrix.length, n=matrix[0].length;

Rotate an array of n elements to the right by k steps. For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].这题要求in-place。 思路和reverse words in a string II 一样: 矩阵转置