原文链接: https://leetcode-cn.com/problems/smallest-string-starting-from-leaf 英文原文You are given the root of a binary tree where each node has a value in the range [0, 25] representing the letters 'a' to 'z'. Return the lexicographically smallest string t…

原文链接: https://leetcode-cn.com/problems/add-to-array-form-of-integer 英文原文The array-form of an integer num is an array representing its digits in left to right order. For example, for num = 1321, the array form is [1,3,2,1]. Given num, the array-form o…

原文链接: https://leetcode-cn.com/problems/satisfiability-of-equality-equations 英文原文You are given an array of strings equations that represent relationships between variables where each string equations[i] is of length 4 and takes one of two different fo…

原文链接: https://leetcode-cn.com/problems/broken-calculator 英文原文There is a broken calculator that has the integer startValue on its display initially. In one operation, you can: multiply the number on display by 2, or subtract 1 from the number on displ…

原文链接: https://leetcode-cn.com/problems/subarrays-with-k-different-integers 英文原文Given an integer array nums and an integer k, return the number of good subarrays of nums. A good array is an array where the number of different integers in that array is…

原文链接: https://leetcode-cn.com/problems/cousins-in-binary-tree 英文原文Given the root of a binary tree with unique values and the values of two different nodes of the tree x and y, return true if the nodes corresponding to the values x and y in the tree a…

原文链接: https://leetcode-cn.com/problems/minimum-number-of-k-consecutive-bit-flips 英文原文You are given a binary array nums and an integer k. A k-bit flip is choosing a subarray of length k from nums and simultaneously changing every 0 in the subarray to …

原文链接: https://leetcode-cn.com/problems/number-of-squareful-arrays 英文原文An array is squareful if the sum of every pair of adjacent elements is a perfect square. Given an integer array nums, return the number of permutations of nums that are squareful. …

原文链接: https://leetcode-cn.com/problems/find-the-town-judge 英文原文In a town, there are n people labeled 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. Ever…

原文链接: https://leetcode-cn.com/problems/maximum-binary-tree-ii 英文原文A maximum tree is a tree where every node has a value greater than any other value in its subtree. You are given the root of a maximum binary tree and an integer val. Just as in the pr…

原文链接: https://leetcode-cn.com/problems/available-captures-for-rook 英文原文On an 8 x 8 chessboard, there is exactly one white rook 'R' and some number of white bishops 'B', black pawns 'p', and empty squares '.'. When the rook moves, it chooses one of fo…

原文链接: https://leetcode-cn.com/problems/minimum-cost-to-merge-stones 英文原文There are n piles of stones arranged in a row. The ith pile has stones[i] stones. A move consists of merging exactly k consecutive piles into one pile, and the cost of this move …

原文链接: https://leetcode-cn.com/problems/grid-illumination 英文原文There is a 2D grid of size n x n where each cell of this grid has a lamp that is initially turned off. You are given a 2D array of lamp positions lamps, where lamps[i] = [rowi, coli] indica…

原文链接: https://leetcode-cn.com/problems/find-common-characters 英文原文Given a string array words, return an array of all characters that show up in all strings within the words (including duplicates). You may return the answer in any order. Example 1: In…

原文链接: https://leetcode-cn.com/problems/check-if-word-is-valid-after-substitutions 英文原文Given a string s, determine if it is valid. A string s is valid if, starting with an empty string t = "", you can transform t into s after performing the following …

原文链接: https://leetcode-cn.com/problems/max-consecutive-ones-iii 英文原文Given a binary array nums and an integer k, return the maximum number of consecutive 1's in the array if you can flip at most k 0's. Example 1: Input: nums = [1,1,1,0,0,0,1,1,1,1,0],…

原文链接: https://leetcode-cn.com/problems/clumsy-factorial 英文原文The factorial of a positive integer n is the product of all positive integers less than or equal to n. For example, factorial(10) = 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1. We make a clumsy f…

原文链接: https://leetcode-cn.com/problems/minimum-domino-rotations-for-equal-row 英文原文In a row of dominoes, tops[i] and bottoms[i] represent the top and bottom halves of the ith domino. (A domino is a tile with two numbers from 1 to 6 - one on each half …

原文链接: https://leetcode-cn.com/problems/construct-binary-search-tree-from-preorder-traversal 英文原文Given an array of integers preorder, which represents the preorder traversal of a BST (i.e., binary search tree), construct the tree and return its root. …

原文链接: https://leetcode-cn.com/problems/complement-of-base-10-integer 英文原文The complement of an integer is the integer you get when you flip all the 0's to 1's and all the 1's to 0's in its binary representation. For example, The integer 5 is "101" in …

原文链接: https://leetcode-cn.com/problems/pairs-of-songs-with-total-durations-divisible-by-60 英文原文You are given a list of songs where the ith song has a duration of time[i] seconds. Return the number of pairs of songs for which their total duration in s…

原文链接: https://leetcode-cn.com/problems/capacity-to-ship-packages-within-d-days 英文原文A conveyor belt has packages that must be shipped from one port to another within days days. The ith package on the conveyor belt has a weight of weights[i]. Each day,…

原文链接: https://leetcode-cn.com/problems/numbers-with-repeated-digits 英文原文Given an integer n, return the number of positive integers in the range [1, n] that have at least one repeated digit. Example 1: Input: n = 20 Output: 1 Explanation: The only pos…

原文链接: https://leetcode-cn.com/problems/partition-array-into-three-parts-with-equal-sum 英文原文Given an array of integers arr, return true if we can partition the array into three non-empty parts with equal sums. Formally, we can partition the array if w…

原文链接: https://leetcode-cn.com/problems/best-sightseeing-pair 英文原文You are given an integer array values where values[i] represents the value of the ith sightseeing spot. Two sightseeing spots i and j have a distance j - i between them. The score of a …

原文链接: https://leetcode-cn.com/problems/smallest-integer-divisible-by-k 英文原文Given a positive integer k, you need to find the length of the smallest positive integer n such that n is divisible by k, and n only contains the digit 1. Return the length of…

原文链接: https://leetcode-cn.com/problems/binary-string-with-substrings-representing-1-to-n 英文原文Given a binary string s and a positive integer n, return true if the binary representation of all the integers in the range [1, n] are substrings of s, or fa…

原文链接: https://leetcode-cn.com/problems/convert-to-base-2 英文原文Given an integer n, return a binary string representing its representation in base -2. Note that the returned string should not have leading zeros unless the string is "0". Example 1: Input…

原文链接: https://leetcode-cn.com/problems/binary-prefix-divisible-by-5 英文原文You are given a binary array nums (0-indexed). We define xi as the number whose binary representation is the subarray nums[0..i] (from most-significant-bit to least-significant-b…

原文链接: https://leetcode-cn.com/problems/next-greater-node-in-linked-list 英文原文You are given the head of a linked list with n nodes. For each node in the list, find the value of the next greater node. That is, for each node, find the value of the first …