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Given a binary matrixA, we want to flip the image horizontally, then invert it, and return the resulting image.To flip an image horizontally means that each row of the image is reversed. For examp...

Given an arrayAof non-negative integers, return an array consisting of all the even elements ofA, followed by all the odd elements ofA.You may return any answer array that satisfies this conditi...

Given an array of integersAsorted in non-decreasing order,return an array of the squares of each number,also in sorted non-decreasing order.Example 1:Input: [-4,-1,0,3,10]Output: [0,1,9,16,1...

Given an array of2nintegers, your task is to group these integers intonpairs of integer, say (a1, b1), (a2, b2), ..., (an, bn) which makes sum of min(ai, bi) for all i from 1 to n as large as poss...

Students are asked to stand in non-decreasing order of heights for an annual photo.Return the minimum number of students not standing in the right positions. (This is the number of students that mu...

此类题目就是花式遍历2维数组，我个人并不喜欢。498.Diagonal TraverseGiven a matrix of M x N elements (M rows, N columns), return all elements of the matrix in diagonal order as shown in the below image.Example:I...

Most Common Word Prison Cells After N Days K Closest Points to Origin Reorder Log Files Partition Labels Min Cost to Add New Roads Min distance to remove the obstacle Roll Dice Min Cost to Con...

Given a fixed lengtharrayarrof integers, duplicate each occurrence of zero, shifting the remaining elements to the right.Note that elements beyond the length of the original array are not written...

141 Linked List CycleGiven a linked list, determine if it has a cycle in it.To represent a cycle in the given linked list, we use an integerposwhich represents the position (0-indexed)in the l...

HashTableis a data structure which organizes data usinghash functionsin order to supportquick insertion and search.In this article, we will take a look at the principle of the hash table.一 自己定...

1. Usage 用法// "static void main" must be defined in a public class.public class Main { public static void main(String[] args) { // 1. Initialize a queue. Queue<Integer> q...

License Key Formatting Unique Email Addresses Fruit Into Baskets Odd Even Jump Maximum Area Serving Cake Min Days to Bloom Fill Matrix Compare Strings Largest Subarray Length K Decreasing Sub...

The count-and-say sequence is the sequence of integers with the first five terms as following:1. 12. 113. 214. 12115. 1112211is read off as"one 1"or11.11is read off ...

这是一道谷歌会考的题目Given a binary tree, count the number of uni-value subtrees.A Uni-value subtree means all nodes of the subtree have the same value.Example :Input: root = [5,1,5,5,5,null,5] ...

You are climbing a stair case. It takesnsteps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?Note:Givennwill be a positive...

Given an arrayAof positive integers, letSbe the sum of the digits of the minimal element ofA.Return 0 ifSis odd, otherwise return 1.Example 1:Input: [99,77,33,66,55]Output: 1Explana...

Given an arraynums, write a function to move all0's to the end of it while maintaining the relative order of the non-zero elements.Example:Input: [0,1,0,3,12]Output: [1,3,12,0,0]Note:You m...

Given an arrayAof non-negative integers, half of the integers in A are odd, and half of the integers are even.Sort the array so that wheneverA[i]is odd,iis odd; and wheneverA[i]is even,iis...

Givennnon-negative integersa1,a2, ...,an, where each represents a point at coordinate (i,ai).nvertical lines are drawn such that the two endpoints of lineiis at (i,ai) and (i, 0). Find two...

Given a valid (IPv4) IPaddress, return a defanged version of that IP address.AdefangedIP addressreplaces every period"."with"[.]".Example 1:Input: address = "1.1.1.1"Output: "1[.]1[....

TheFibonacci numbers, commonly denotedF(n)form a sequence, called theFibonacci sequence, such that each number is the sum of the two preceding ones, starting from0and1. That is,F(0) = 0, F(...

On an 8 x 8 chessboard, there is one white rook. There also may be empty squares, white bishops, and black pawns. These are given as characters 'R', '.', 'B', and 'p' respectively. Uppercase charact...

Given two listsAandB, andBis an anagram ofA.Bis an anagram ofAmeansBis made by randomizing the order of the elements inA.We want to find anindex mappingP, fromAtoB. A mappingP[i] =...

Given an arrayAof distinct integers sorted in ascending order, return the smallest indexithat satisfiesA[i] == i. Return-1if no suchiexists.Example 1:Input: [-10,-5,0,3,7]Output: 3...

Given an arrayAof strings made only from lowercase letters, return a list of all characters that show up in all strings within the list(including duplicates).For example, if a character occurs 3 ...

Given amatrixA, return the transpose ofA.The transpose of a matrix is the matrix flipped over it's main diagonal, switching the row and column indices of the matrix.Example 1:Input: [[1,2,3]...

Given an array of integers, returnindicesof the two numbers such that they add up to a specific target.You may assume that each input would haveexactlyone solution, and you may not use thesame...

Operations in Array// "static void main" must be defined in a public class.public class Main { public static void main(String[] args) { // 1. Initialize int[] a0 = new int[5];...

You're given stringsJrepresenting the types of stones that are jewels, andSrepresenting the stones you have. Each character inSis a type of stone you have. You want to know how many of the ston...

先吐槽一下这个难度，咋也不能是easy啊，和其他easy的不在一个量级。Given a list of scores of different students, return the average score of each student'stop five scoresinthe order of each student's id.Each entryitems[i]h...

Given a stringS, remove the vowels'a','e','i','o', and'u'from it, and return the new string.Example 1:Input: "leetcodeisacommunityforcoders"Output: "ltcdscmmntyfrcdrs"Example 2:Inpu...

1 动态规划简介动态规划在查找有很多重叠子问题的情况的最优解时有效。它将问题重新组合成子问题。为了避免多次解决这些子问题，它们的结果都逐渐被计算并被保存，从简单的问题直到整个问题都被解决。因此，动态规划保存递归时的结果，因而不会在解决同样的问题时花费时间。动态规划只能应用于有最优子结构的问题。最优子结构的意思是局部最优解能决定全局最优解（对有些问题这个要求并不能完全满足，故有时需要引入一定的近...