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Aboomerangis a set of 3 points that are all distinct andnotin a straight line.Given a listof three points in the plane, return whether these points are a boomerang.Example 1:Input: [[1...

Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters.This is case sensitive, for example "Aa" is not cons...

A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59).Each LED represents a zero or one, with the least significant bit on...

In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1.Two nodes of a binary tree are cousins if they have the same depth, but have different parents.We...

The Hamming distance between two integers is the number of positions at which the corresponding bits are different.Given two integers x and y, calculate the Hamming distance.Note:0 ≤ x, y < 2...

We have an array A of integers, and an array queries of queries.For the i-th query val = queries[i][0], index = queries[i][1], we add val to A[index].  Then, the answer to the i-th query is the sum...

Related tops: DFS & RecursionGiven a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.Note: A leaf i...

贪心算法Given two integers A and B, return any string S such that:S has length A + B and contains exactly A 'a' letters, and exactly B 'b'letters; The substring 'aaa' does not occur in S; The subst...

Given an array of 2n integers, your task is to group these integers into n pairs 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 pos...

backtracking + dfs + recursive 784. Letter Case PermutationEasy49661FavoriteShareGiven a string S, we can transform every letter individually to be lowercase or uppercase to create another st...

 递归专题1Given a balanced parentheses string S, compute the score of the string based on the following rule:() has score 1 AB has score A + B, where A and B are balanced parentheses strings. (A) h...

Given an array of integers A, find the number of triples of indices (i, j, k) such that:0 <= i < A.length 0 <= j < A.length 0 <= k < A.length A[i] & A[j] & A[k] == 0, w...

Given a 32-bit signed integer, reverse digits of an integer.Example 1:Input: 123Output: 321Example 2:Input: -123Output: -321Example 3:Input: 120Output: 21Note:Assume we are de...

https://leetcode-cn.com/problems/contiguous-array/ 给定一个二进制数组, 找到含有相同数量的 0 和 1 的最长连续子数组（的长度）。 示例 1:输入: [0,1]输出: 2说明: [0, 1] 是具有相同数量0和1的最长连续子数组。示例 2:输入: [0,1,0]输出: 2说明: [0, 1] (或 [1, ...

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Given an array of integers A sorted 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,...

In a town, there are N people labelled from 1 to N.  There is a rumor that one of these people is secretly the town judge.If the town judge exists, then:The town judge trusts nobody. Everybody (...

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...

A valid parentheses string is either empty(""),"(" + A + ")", orA + B, whereAandBare valid parentheses strings, and+represents string concatenation. For example,"","()","(())()", and"(()...

Given a numberN, return a string consisting of"0"s and"1"sthat represents its value in base-2(negative two).The returned string must have no leading zeroes, unless the string is"0".Exam...

We are given a linked list withheadas the first node. Let's number thenodes in the list:node_1, node_2, node_3, ...etc.Each node may have anext largervalue: fornode_i,next_larger(node_i)...

Given an arrayAof0s and1s, considerN_i: the i-th subarray fromA[0]toA[i]interpretedas a binary number (from most-significant-bit to least-significant-bit.)Return a list of booleansanswer...

Given a binary stringS(a string consisting only of '0' and '1's) and a positive integerN, return true if and only if for every integer X from 1 to N, the binary representation of X is a substring ...

Given a binary tree, flatten it to a linked list in-place.For example, given the following tree: 1 / \ 2 5 / \ \3 4 6The flattened tree should look like:1 \ 2 \ ...

Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.Note:The given integer is guaranteed to fit within the range of a ...

Given 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 linked list where tail c...

Given a stringsand anon-emptystringp, find all the start indices ofp's anagrams ins.Strings consists of lowercase English letters only and the length of both stringssandpwill not be larg...

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree[1,2,2,3,4,4,3]is symmetric: 1 / \ 2 2 / \ / \3 4 4 3...

In a list of songs, thei-thsong has a duration oftime[i]seconds.Return the number of pairs of songs for which their totalduration in seconds is divisible by60. Formally, we want the number ...

Every non-negative integerNhas a binary representation. For example,5can be represented as"101"in binary,11as"1011"in binary, and so on. Note that except forN = 0, there are no leading z...

Find thenthdigit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...Note:nis positive and will fit within the range of a 32-bit signed integer (n< 231).Example 1:Inp...

Given an arrayAof integers, wemustmodify the array in the following way: we choose aniand replaceA[i]with-A[i], and we repeat this processKtimes in total. (We may choose the same indexi...

We are given that the string"abc"is valid.From any valid stringV, we may splitVinto two piecesXandYsuch thatX + Y(Xconcatenated withY) is equal toV. (XorYmay be empty.) Then,X + ...

A subarray A[i], A[i+1], ..., A[j] of A is said to be turbulent if and only if:For i <= k < j, A[k] > A[k+1] when k is odd, and A[k] < A[k+1] when k is even; OR, for i <= k < j, ...

Given an array A of positive lengths, return the largest perimeter of a triangle with non-zero area, formed from 3 of these lengths.If it is impossible to form any triangle of non-zero area, return...

Every email consists of a local name and a domain name, separated by the @ sign.For example, in alice@leetcode.com, alice is the local name, and leetcode.com is the domain name.Besides lowercase l...

Given an array A, partition it into two (contiguous) subarrays left and right so that:Every element in left is less than or equal to every element in right. left and right are non-empty. left has ...

In a deck of cards, each card has an integer written on it.Return true if and only if you can choose X >= 2 such that it is possible to split the entire deck into 1 or more groups of cards, where...

A string S of lowercase letters is given. We want to partition this string into as many parts as possible so that each letter appears in at most one part, and return a list of integers representing th...

Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.Example 1:Input: [3,0,1]Output: 2Example 2:Input: [9,6,4,2,3,5,7,0,1]O...