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Given amatrix, and atarget, return the number of non-empty submatrices that sum totarget.A submatrixx1, y1, x2, y2is the set of all cellsmatrix[x][y]withx1 <= x <= x2andy1 <= y &l...

(This problem is the same asMinimize Malware Spread, with the differences bolded.)In a network of nodes, each nodeiis directly connected to another nodejif and only ifgraph[i][j] = 1.Some no...

LeetCode wants to give one of its best employees the option to travel amongNcities to collect algorithm problems. But all work and no play makes Jack a dull boy, you could take vacations in some par...

Given anon-emptybinary tree, find the maximum path sum.For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connectio...

Given a binary tree, we install cameras on the nodes of the tree.Each camera ata node can monitorits parent, itself, and its immediate children.Calculate the minimum number of cameras needed to...

Given a binary tree, return thepostordertraversal of its nodes' values.Example:Input:[1,null,2,3] 1 \ 2 / 3Output:[3,2,1]Follow up:Recursive solution is trivial, coul...

Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Example 1:Input: [1,3,null,null,2] 1 /3 \ 2Output: [3,1,null,nul...

An undirected, connectedtree withNnodes labelled0...N-1andN-1edgesaregiven.Theith edge connects nodesedges[i][0]andedges[i][1]together.Return a listans, whereans[i]is the sum of th...

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be...

Given a non-empty 2D matrixmatrixand an integerk, find the max sum of a rectangle in thematrixsuch that its sum is no larger thank.Example:Input: matrix = [[1,0,1],[0,-2,3]], k = 2Output: ...

On an N x Ngrid, each squaregrid[i][j]represents the elevation at that point(i,j).Now rain starts to fall. At timet, the depth of the water everywhere ist. You can swim from a square to anothe...

Given an array which consists of non-negative integers and an integerm, you can split the array intomnon-empty continuous subarrays. Write an algorithm to minimize the largest sum among thesemsub...

Nearly every one have used theMultiplication Table. But could you find out thek-thsmallest number quickly from the multiplication table?Given the heightmand the lengthnof am * nMultiplicatio...

A sorted listAcontains 1, plus some number of primes. Then, for every p < q in the list, we consider the fraction p/q.What is theK-th smallest fraction considered? Return your answer as an a...

Nearly every one have used theMultiplication Table. But could you find out thek-thsmallest number quickly from the multiplication table?Given the heightmand the lengthnof am * nMultiplicatio...

The demons had captured the princess (P) and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of M x N rooms laid out in a 2D grid. Our valiant knight (K) was initially pos...

Given an integer array, return the k-th smallestdistanceamong all the pairs. The distance of a pair (A, B) is defined as the absolute difference between A and B.Example 1:Input:nums = [1,3,1]...

On an N x Ngrid, each squaregrid[i][j]represents the elevation at that point(i,j).Now rain starts to fall. At timet, the depth of the water everywhere ist. You can swim from a square to anothe...

You have a number of envelopes with widths and heights given as a pair of integers(w, h). One envelope can fit into another if and only if both the width and height of one envelope is greater than th...

For an integer n, we call k>=2 agood baseof n, if all digits of n base k are 1.Now given a string representing n, you should return the smallest good base of n in string format.Example 1:I...

A positive integerismagicalif it is divisible by eitherAorB.Return theN-th magical number. Since the answer may be very large,return it modulo10^9 + 7.Example 1:Input: N = 1, A = 2...

There are two sorted arraysnums1andnums2of size m and n respectively.Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).You may assumenums1andn...

164.Maximum GapHard450124FavoriteShareGiven an unsorted array, find the maximum difference between the successive elements in its sorted form.Return 0 if the array contains less than 2 elemen...

You are installing a billboard and want it to have the largest height. The billboard will have two steel supports, one on each side. Each steel support must be an equal height.You have a collectio...

552.Student Attendance Record IIGiven a positive integern, return the number of all possible attendance records with length n, which will be regarded as rewardable. The answer may be very large, r...

273.Integer to English WordsConvert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231- 1.Example 1:Input: 123Output: "One Hundred Twen...

403.Frog JumpHard47256FavoriteShareA frog is crossing a river. The river is divided into x units and at each unit there may or may not exist a stone. The frog can jump on a stone, but it must n...

Say you have an array for which theithelement is the price of a given stock on dayi.Design an algorithm to find the maximum profit. You may complete at mostktransactions.Note:You may not eng...

312.Burst BalloonsHard124534FavoriteShareGivennballoons, indexed from0ton-1. Each balloon is painted with a number on it represented by arraynums. You are asked to burst all the balloons....

There areNchildren 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 one ca...

123.Best Time to Buy and Sell Stock IIIHard98953FavoriteShareSay you have an array for which theithelement is the price of a given stock on dayi.Design an algorithm to find the maximum pro...

Given a list of words (without duplicates), please write a program that returns all concatenated words in the given list of words.A concatenated word is defined as a string that is comprised entirel...

466.Count The RepetitionsHard10279FavoriteShareDefineS = [s,n]as the string S which consists of n connected strings s. For example,["abc", 3]="abcabcabc".On the other hand, we define that...

Given a stringSand a stringT, count the number of distinct subsequences ofSwhich equalsT.A subsequence of a string is a new string which is formed from the original string by deleting some (ca...

97.Interleaving StringHard72735FavoriteShareGivens1,s2,s3, find whethers3is formed by the interleaving ofs1ands2.Example 1:Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbcbcac"Outp...

72.Edit DistanceHard197930FavoriteShareGiven two wordsword1andword2, find the minimum number of operations required to convertword1toword2.You have the following 3 operations permitted ...

212.Word Search IIHard107368FavoriteShareGiven a 2D board and a list of words from the dictionary, find all words in the board.Each word must be constructed from letters of sequentially adjac...

In the video game Fallout 4, the quest "Road to Freedom" requires players to reach a metal dial called the "Freedom Trail Ring", and use the dial to spell a specific keyword in order to open the door....

Given two words (beginWordandendWord), and a dictionary's word list, find all shortest transformation sequence(s) frombeginWordtoendWord, such that:Only one letter can be changed at a time Eac...

Given anm x nmatrix of positive integers representing the height of each unit cell in a 2D elevation map, compute the volume of water it is able to trap after raining.Note:Bothmandnare le...