原文链接: https://leetcode-cn.com/problems/last-substring-in-lexicographical-order 英文原文Given a string s, return the last substring of s in lexicographical order. Example 1: Input: s = "abab" Output: "bab" Explanation: The substrings are ["a", "ab", "aba"…

原文链接: https://leetcode-cn.com/problems/grumpy-bookstore-owner 英文原文There is a bookstore owner that has a store open for n minutes. Every minute, some number of customers enter the store. You are given an integer array customers of length n where custo…

原文链接: https://leetcode-cn.com/problems/previous-permutation-with-one-swap 英文原文Given an array of positive integers arr (not necessarily distinct), return the lexicographically largest permutation that is smaller than arr, that can be made with exactly…

原文链接: https://leetcode-cn.com/problems/distant-barcodes 英文原文In a warehouse, there is a row of barcodes, where the ith barcode is barcodes[i]. Rearrange the barcodes so that no two adjacent barcodes are equal. You may return any answer, and it is guar…

原文链接: https://leetcode-cn.com/problems/number-of-submatrices-that-sum-to-target 英文原文Given a matrix and a target, return the number of non-empty submatrices that sum to target. A submatrix x1, y1, x2, y2 is the set of all cells matrix[x][y] with x1 <=…

原文链接: https://leetcode-cn.com/problems/greatest-common-divisor-of-strings 英文原文For two strings s and t, we say "t divides s" if and only if s = t + ... + t (t concatenated with itself 1 or more times) Given two strings str1 and str2, return the larges…

原文链接: https://leetcode-cn.com/problems/flip-columns-for-maximum-number-of-equal-rows 英文原文You are given an m x n binary matrix matrix. You can choose any number of columns in the matrix and flip every cell in that column (i.e., Change the value of the…

原文链接: https://leetcode-cn.com/problems/occurrences-after-bigram 英文原文Given two strings first and second, consider occurrences in some text of the form "first second third", where second comes immediately after first, and third comes immediately after …

原文链接: https://leetcode-cn.com/problems/insufficient-nodes-in-root-to-leaf-paths 英文原文Given the root of a binary tree and an integer limit, delete all insufficient nodes in the tree simultaneously, and return the root of the resulting binary tree. A no…

原文链接: https://leetcode-cn.com/problems/smallest-subsequence-of-distinct-characters 英文原文Given a string s, return the lexicographically smallest subsequence of s that contains all the distinct characters of s exactly once. Example 1: Input: s = "bcabc"…

原文链接: https://leetcode-cn.com/problems/duplicate-zeros 英文原文Given a fixed-length integer array arr, duplicate each occurrence of zero, shifting the remaining elements to the right. Note that elements beyond the length of the original array are not wri…

原文链接: https://leetcode-cn.com/problems/largest-values-from-labels 英文原文There is a set of n items. You are given two integer arrays values and labels where the value and the label of the ith element are values[i] and labels[i] respectively. You are als…

原文链接: https://leetcode-cn.com/problems/shortest-common-supersequence 英文原文Given two strings str1 and str2, return the shortest string that has both str1 and str2 as subsequences. If there are multiple valid strings, return any of them. A string s is a…

原文链接: https://leetcode-cn.com/problems/statistics-from-a-large-sample 英文原文You are given a large sample of integers in the range [0, 255]. Since the sample is so large, it is represented by an array count where count[k] is the number of times that k a…

原文链接: https://leetcode-cn.com/problems/car-pooling 英文原文There is a car with capacity empty seats. The vehicle only drives east (i.e., it cannot turn around and drive west). You are given the integer capacity and an array trips where trip[i] = [numPass…

原文链接: https://leetcode-cn.com/problems/find-in-mountain-array 英文原文(This problem is an interactive problem.) You may recall that an array arr is a mountain array if and only if: arr.length >= 3 There exists some i with 0 < i < arr.length - 1 such that…

原文链接: https://leetcode-cn.com/problems/building-h2o 英文原文There are two kinds of threads: oxygen and hydrogen. Your goal is to group these threads to form water molecules. There is a barrier where each thread has to wait until a complete molecule can b…

原文链接: https://leetcode-cn.com/problems/print-foobar-alternately 英文原文Suppose you are given the following code: class FooBar { public void foo() { for (int i = 0; i < n; i++) { print("foo"); } } public void bar() { for (int i = 0; i < n; i++) { print("…

原文链接: https://leetcode-cn.com/problems/brace-expansion-ii 中文题目如果你熟悉 Shell 编程，那么一定了解过花括号展开，它可以用来生成任意字符串。 花括号展开的表达式可以看作一个由 花括号、逗号 和 小写英文字母 组成的字符串，定义下面几条语法规则： 如果只给出单一的元素 x，那么表达式表示的字符串就只有 "x"。R(x) = &#123;x&#125; <ul> <li>例如，表达式 <code>"a"</code> 表示字符串 <c…

原文链接: https://leetcode-cn.com/problems/path-in-zigzag-labelled-binary-tree 英文原文In an infinite binary tree where every node has two children, the nodes are labelled in row order. In the odd numbered rows (ie., the first, third, fifth,...), the labelli…

原文链接: https://leetcode-cn.com/problems/distribute-candies-to-people 英文原文We distribute some number of candies, to a row of n = num_people people in the following way: We then give 1 candy to the first person, 2 candies to the second person, and so on …

原文链接: https://leetcode-cn.com/problems/filling-bookcase-shelves 英文原文You are given an array books where books[i] = [thicknessi, heighti] indicates the thickness and height of the ith book. You are also given an integer shelfWidth. We want to place the…

原文链接: https://leetcode-cn.com/problems/parsing-a-boolean-expression 英文原文Return the result of evaluating a given boolean expression, represented as a string. An expression can either be: "t", evaluating to True; "f", evaluating to False; "!(expr)", ev…

原文链接: https://leetcode-cn.com/problems/print-in-order 英文原文Suppose we have a class: public class Foo { public void first() { print("first"); } public void second() { print("second"); } public void third() { print("third"); } } The same instance of Foo…

原文链接: https://leetcode-cn.com/problems/defanging-an-ip-address 英文原文Given a valid (IPv4) IP address, return a defanged version of that IP address. A defanged IP address replaces every period "." with "[.]". Example 1: Input: address = "1.1.1.1" Output…

原文链接: https://leetcode-cn.com/problems/corporate-flight-bookings 英文原文There are n flights that are labeled from 1 to n. You are given an array of flight bookings bookings, where bookings[i] = [firsti, lasti, seatsi] represents a booking for flights fi…

原文链接: https://leetcode-cn.com/problems/delete-nodes-and-return-forest 英文原文Given the root of a binary tree, each node in the tree has a distinct value. After deleting all nodes with a value in to_delete, we are left with a forest (a disjoint union of …

原文链接: https://leetcode-cn.com/problems/maximum-nesting-depth-of-two-valid-parentheses-strings 英文原文A string is a valid parentheses string (denoted VPS) if and only if it consists of "(" and ")" characters only, and: It is the empty string, or It can b…

原文链接: https://leetcode-cn.com/problems/mean-of-array-after-removing-some-elements 英文原文Given an integer array arr, return the mean of the remaining integers after removing the smallest 5% and the largest 5% of the elements. Answers within 10-5 of the …

原文链接: https://leetcode-cn.com/problems/iterator-for-combination 英文原文Design the CombinationIterator class: CombinationIterator(string characters, int combinationLength) Initializes the object with a string characters of sorted distinct lowercase Engli…