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Given two non-negative integersnum1andnum2represented as strings, return the product ofnum1andnum2, also represented as a string.Example 1:Input: num1 = "2", num2 = "3"Output: "6"Exampl...

Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations incandidateswhere the candidate numbers sums totarget.Each number incandidatesmay...

Given a sorted arraynums, remove the duplicatesin-placesuch that duplicates appeared at mosttwiceand return the new length.Do not allocate extra space for another array, you must do this bymod...

Implementnext 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 o...

Given an arraynumsofnintegers and an integertarget, find three integers innumssuch that the sum is closest totarget. Return the sum of the three integers. You may assume that each input would ...

Given an arraynumsofnintegers and an integertarget, are there elementsa,b,c, anddinnumssuch thata+b+c+d=target? Find all unique quadruplets in the array which gives the sum oftar...

Given the root of a binarysearchtree with distinct values, modify it so that everynodehas a new value equal to the sum of the values of the original tree that are greater than or equal tonode.val...

Given two integersdividendanddivisor, divide two integers without using multiplication, division and mod operator.Return the quotient after dividingdividendbydivisor.The integer division sho...

Design and implement a data structure forLeast Recently Used (LRU) cache. It should support the following operations:getandput.get(key)- Get the value (will always be positive) of the key if th...

Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes.You should try to do it in p...

There areNgas stations along a circular route, where the amount of gas at stationiisgas[i].You have a car with an unlimited gas tank and it costscost[i]of gas to travel from stationito its ...

Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array.Formally the function should:Return true if there existsi, j, ksuch thatarr[i]<arr[j...

Find the length of the longest substringTof a given string (consists of lowercase letters only) such that every character inTappears no less thanktimes.Example 1:Input:s = "aaabb", k = 3...

Given four lists A, B, C, D of integer values, compute how many tuples(i, j, k, l)there are such thatA[i] + B[j] + C[k] + D[l]is zero.To make problem a bit easier, all A, B, C, D have same lengt...

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.If the fractional part is repeating, enclose the repeating part in parentheses.Exa...

Evaluate the value of an arithmetic expression inReverse Polish Notation.Valid operators are+,-,*,/. Each operand may be an integer or another expression.Note:Division between two integers ...

You are given coins of different denominations and a total amount of moneyamount. Write a function to compute the fewest number of coins that you need to make up that amount. If that amount of money ...

Write an efficient algorithm that searches for a value in anmxnmatrix. This matrix has the following properties:Integers in each row are sorted in ascending from left to right. Integers in each...

Implement a basic calculator to evaluate a simple expression string.The expression string contains onlynon-negativeintegers,+,-,*,/operators and empty spaces. The integer division should tru...

Given acompletebinary tree, count the number of nodes.Note:Definition of a complete binary tree fromWikipedia:In a complete binary tree every level, except possibly the last, is completely fil...

Find the sum of all left leaves in a given binary tree.Example: 3 / \ 9 20 / \ 15 7There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24....

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.According to thedefinition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p...

Given a list of non negative integers, arrange them such that they form the largest number.Example 1:Input: [10,2]Output: "210"Example 2:Input: [3,30,34,5,9]Output: "9534330"将数组中的数组合成一...

Given a strings, partitionssuch that every substring of the partition is a palindrome.Return all possible palindrome partitioning ofs.Example:Input:"aab"Output:[ ["aa","b"], ["a","a"...

Given a 2D board and a word, find if the word exists in the grid.The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically n...

ShareGiven asetof candidate numbers (candidates)(without duplicates)and a target number (target), find all unique combinations incandidateswhere the candidate numbers sums totarget.Thesame...

Given a matrix ofmxnelements (mrows,ncolumns), return all elements of the matrix in spiral order.Example 1:Input:[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ]]Output: [1,2,3,6,9,8,7,4,5]...

Determine if a9x9 Sudoku boardis valid.Only the filled cells need to be validatedaccording to the following rules:Each rowmust contain thedigits1-9without repetition. Each column must conta...

Givennpairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, givenn= 3, a solution set is:[ "((()))", "(()())", "(())()", "()(())"...

Given an arraynumsofnintegers, are there elementsa,b,cinnumssuch thata+b+c= 0? Find all unique triplets in the array which gives the sum of zero.Note:The solution set must not cont...

Given amxnmatrix, if an element is 0, set its entire row and column to 0. Do itin-place.Example 1:Input: [ [1,1,1], [1,0,1], [1,1,1]]Output: [ [1,0,1], [0,0,0], [1,0,1]]将...

Given a collection of intervals, merge all overlapping intervals.Example 1:Input: [[1,3],[2,6],[8,10],[15,18]]Output: [[1,6],[8,10],[15,18]]Explanation: Since intervals [1,3] and [2,6] overlaps...

Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at that position.Determine if yo...

Implementpow(x,n), which calculatesxraised to the powern(xn).Example 1:Input: 2.00000, 10Output: 1024.00000Example 2:Input: 2.10000, 3Output: 9.26100Example 3:Input: 2.00000, ...

Given an unsorted integer array, find the smallest missingpositive integer.Example 1:Input: [1,2,0]Output: 3Example 2:Input: [3,4,-1,1]Output: 2Example 3:Input: [7,8,9,11,12]Outpu...

Given an array of strings, group anagrams together.Example:Input: ["eat", "tea", "tan", "ate", "nat", "bat"],Output:[ ["ate","eat","tea"], ["nat","tan"], ["bat"]]把相同字母，不同顺序的单词放在一起。思路就...

Given an array of integersnumssorted in ascending order, find the starting and ending position of a giventargetvalue.Your algorithm's runtime complexity must be in the order ofO(logn).If the...

Given a string containing digits from2-9inclusive, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is giv...

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...

Implementatoiwhichconverts a string to an integer.The function first discards as many whitespace characters as necessary until the first non-whitespace character is found. Then, starting from thi...