原文链接: https://leetcode-cn.com/problems/coin-change 英文原文You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money. Return the fewest number of coins that you need to m…

原文链接: https://leetcode-cn.com/problems/power-of-three 英文原文Given an integer n, return true if it is a power of three. Otherwise, return false. An integer n is a power of three, if there exists an integer x such that n == 3x. Example 1: Input: n = 27 O…

原文链接: https://leetcode-cn.com/problems/count-of-range-sum 英文原文Given an integer array nums and two integers lower and upper, return the number of range sums that lie in [lower, upper] inclusive. Range sum S(i, j) is defined as the sum of the elements …

原文链接: https://leetcode-cn.com/problems/odd-even-linked-list 英文原文Given the head of a singly linked list, group all the nodes with odd indices together followed by the nodes with even indices, and return the reordered list. The first node is considered…

原文链接: https://leetcode-cn.com/problems/longest-increasing-path-in-a-matrix 英文原文Given an m x n integers matrix, return the length of the longest increasing path in matrix. From each cell, you can either move in four directions: left, right, up, or dow…

原文链接: https://leetcode-cn.com/problems/patching-array 英文原文Given a sorted integer array nums and an integer n, add/patch elements to the array such that any number in the range [1, n] inclusive can be formed by the sum of some elements in the array. R…

原文链接: https://leetcode-cn.com/problems/verify-preorder-serialization-of-a-binary-tree 英文原文One way to serialize a binary tree is to use preorder traversal. When we encounter a non-null node, we record the node's value. If it is a null node, we record …

原文链接: https://leetcode-cn.com/problems/reconstruct-itinerary 英文原文You are given a list of airline tickets where tickets[i] = [fromi, toi] represent the departure and the arrival airports of one flight. Reconstruct the itinerary in order and return it.…

原文链接: https://leetcode-cn.com/problems/increasing-triplet-subsequence 英文原文Given an integer array nums, return true if there exists a triple of indices (i, j, k) such that i < j < k and nums[i] < nums[j] < nums[k]. If no such indices exists, return fa…

原文链接: https://leetcode-cn.com/problems/palindrome-pairs 英文原文Given a list of unique words, return all the pairs of the distinct indices (i, j) in the given list, so that the concatenation of the two words words[i] + words[j] is a palindrome. Example 1…

原文链接: https://leetcode-cn.com/problems/house-robber-iii 英文原文The thief has found himself a new place for his thievery again. There is only one entrance to this area, called root. Besides the root, each house has one and only one parent house. After a …

原文链接: https://leetcode-cn.com/problems/counting-bits 英文原文Given an integer n, return an array ans of length n + 1 such that for each i (0 <= i <= n), ans[i] is the number of 1's in the binary representation of i. Example 1: Input: n = 2 Output: [0,1,1…

原文链接: https://leetcode-cn.com/problems/flatten-nested-list-iterator 英文原文You are given a nested list of integers nestedList. Each element is either an integer or a list whose elements may also be integers or other lists. Implement an iterator to flatt…

原文链接: https://leetcode-cn.com/problems/power-of-four 英文原文Given an integer n, return true if it is a power of four. Otherwise, return false. An integer n is a power of four, if there exists an integer x such that n == 4x. Example 1: Input: n = 16 Outp…

原文链接: https://leetcode-cn.com/problems/integer-break 英文原文Given an integer n, break it into the sum of k positive integers, where k >= 2, and maximize the product of those integers. Return the maximum product you can get. Example 1: Input: n = 2 Outpu…

原文链接: https://leetcode-cn.com/problems/reverse-string 英文原文Write a function that reverses a string. The input string is given as an array of characters s. You must do this by modifying the input array in-place with O(1) extra memory. Example 1: Input:…

原文链接: https://leetcode-cn.com/problems/reverse-vowels-of-a-string 英文原文Given a string s, reverse only all the vowels in the string and return it. The vowels are 'a', 'e', 'i', 'o', and 'u', and they can appear in both cases. Example 1: Input: s = "hel…

原文链接: https://leetcode-cn.com/problems/top-k-frequent-elements 英文原文Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order. Example 1: Input: nums = [1,1,1,2,2,3], k = 2 Output: [1,2] …

原文链接: https://leetcode-cn.com/problems/intersection-of-two-arrays 英文原文Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any order. Example 1: In…

原文链接: https://leetcode-cn.com/problems/intersection-of-two-arrays-ii 英文原文Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must appear as many times as it shows in both arrays and you may retu…

原文链接: https://leetcode-cn.com/problems/data-stream-as-disjoint-intervals 英文原文Given a data stream input of non-negative integers a1, a2, ..., an, summarize the numbers seen so far as a list of disjoint intervals. Implement the SummaryRanges class: Sum…

原文链接: https://leetcode-cn.com/problems/russian-doll-envelopes 英文原文You are given a 2D array of integers envelopes where envelopes[i] = [wi, hi] represents the width and the height of an envelope. One envelope can fit into another if and only if both t…

原文链接: https://leetcode-cn.com/problems/design-twitter 英文原文Design a simplified version of Twitter where users can post tweets, follow/unfollow another user, and is able to see the 10 most recent tweets in the user's news feed. Implement the Twitter cl…

原文链接: https://leetcode-cn.com/problems/max-sum-of-rectangle-no-larger-than-k 英文原文Given an m x n matrix matrix and an integer k, return the max sum of a rectangle in the matrix such that its sum is no larger than k. It is guaranteed that there will be…

原文链接: https://leetcode-cn.com/problems/water-and-jug-problem 英文原文You are given two jugs with capacities jug1Capacity and jug2Capacity liters. There is an infinite amount of water supply available. Determine whether it is possible to measure exactly t…

原文链接: https://leetcode-cn.com/problems/valid-perfect-square 英文原文Given a positive integer num, write a function which returns True if num is a perfect square else False. Follow up: Do not use any built-in library function such as sqrt. Example 1: Inpu…

原文链接: https://leetcode-cn.com/problems/sum-of-two-integers 英文原文Given two integers a and b, return the sum of the two integers without using the operators + and -. Example 1: Input: a = 1, b = 2 Output: 3 Example 2: Input: a = 2, b = 3 Output: 5 Const…

原文链接: https://leetcode-cn.com/problems/super-pow 英文原文Your task is to calculate ab mod 1337 where a is a positive integer and b is an extremely large positive integer given in the form of an array. Example 1: Input: a = 2, b = [3] Output: 8 Example 2:…

原文链接: https://leetcode-cn.com/problems/find-k-pairs-with-smallest-sums 英文原文You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k. Define a pair (u, v) which consists of one element from the first array and one el…

原文链接: https://leetcode-cn.com/problems/guess-number-higher-or-lower 英文原文We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wrong, I will tell you whether t…