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Given a binary tree, find the length of the longest path where each node in the path has the same value. This path may or may not pass through the roo 阅读全文
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Given two strings A and B, find the minimum number of times A has to be repeated such that B is a substring of it. If no such solution, return -1. For 阅读全文
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In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (wi 阅读全文
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You're now a baseball game point recorder. Given a list of strings, each string can be one of the 4 following types: Each round's operation is permane 阅读全文
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Given a time represented in the format "HH:MM", form the next closest time by reusing the current digits. There is no limit on how many times a digit 阅读全文
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博主昨晚正在刷题，突然手机语音大声提示“微信支付收款到账”，把博主吓了一跳，打开一看，居然收到了第一笔打赏，还是博主最喜欢的数字，老开心了～感谢网友对于博主工作的认可与支持，多谢多谢！不管大家是物质打赏(比如扫码发红包，大家打赏时请留下微信号哦，可以跟博主加为好友哈，可以通过在付款方留言中留下你的微 阅读全文
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Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome. Example 1: Example 2: Note: 这道题是之前那道Vali 阅读全文
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Given a string containing only three types of characters: '(', ')' and '*', write a function to check whether this string is valid. We define the vali 阅读全文
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Implement a MapSum class with insert, and sum methods. For the method insert, you'll be given a pair of (string, integer). The string represents the k 阅读全文
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Implement a magic directory with buildDict, and search methods. For the method buildDict, you'll be given a list of non-repetitive words to build a di 阅读全文
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Given an unsorted array of integers, find the length of longest continuous increasing subsequence. Example 1: Example 2: Note: Length of the array wil 阅读全文
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Given an unsorted array of integers, find the number of longest increasing subsequence. Example 1: Input: [1,3,5,4,7] Output: 2 Explanation: The two l 阅读全文
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There is a room with n lights which are turned on initially and 4 buttons on the wall. After performing exactly m unknown operations towards buttons, 阅读全文
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Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly two or zero sub-node. 阅读全文
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Given a non-negative integer, you could swap two digits at most once to get the maximum valued number. Return the maximum valued number you could get. 阅读全文
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Given a binary search tree and the lowest and highest boundaries as L and R, trim the tree so that all its elements lies in [L, R] (R >= L). You might 阅读全文
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Given two integers n and k, you need to construct a list which contains n different positive integers ranging from 1 to n and obeys the following requ 阅读全文
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If the depth of a tree is smaller than 5, then this tree can be represented by a list of three-digits integers. For each integer in this list: Given a 阅读全文
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Given an array with n integers, your task is to check if it could become non-decreasing by modifying at most 1element. We define an array is non-decre 阅读全文
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Given a binary tree with n nodes, your task is to check if it's possible to partition the tree to two trees which have the equal sum of values after r 阅读全文
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Given a binary tree, write a function to get the maximum width of the given tree. The width of a tree is the maximum width among all levels. The binar 阅读全文
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Given a 2D integer matrix M representing the gray scale of an image, you need to design a smoother to make the gray scale of each cell becomes the ave 阅读全文
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You are given an integer array sorted in ascending order (may contain duplicates), you need to split them into several subsequences, where each subseq 阅读全文
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Given a sorted array, two integers k and x, find the k closest elements to x in the array. The result should also be sorted in ascending order. If the 阅读全文
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Initially, there is a Robot at position (0, 0). Given a sequence of its moves, judge if this robot makes a circle, which means it moves back to the or 阅读全文
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You are given an integer array nums with no duplicates. A maximum binary tree can be built recursively from nums using the following algorithm: Create 阅读全文
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Given a Binary Search Tree and a target number, return true if there exist two elements in the BST such that their sum is equal to the given target. E 阅读全文
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Given the root of a binary tree, return all duplicate subtrees. For each kind of duplicate subtrees, you only need to return the root node of any one 阅读全文
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Print a binary tree in an m*n 2D string array following these rules: Example 1: Example 2: Example 3: Note: The height of binary tree is in the range 阅读全文
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Imagine you have a special keyboard with the following keys: Key 1: (A): Print one 'A' on screen. Key 2: (Ctrl-A): Select the whole screen. Key 3: (Ct 阅读全文
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Initially on a notepad only one character 'A' is present. You can perform two operations on this notepad for each step: Copy All: You can copy all the 阅读全文
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In the world of Dota2, there are two parties: the Radiant and the Dire. The Dota2 senate consists of senators coming from two parties. Now the senate 阅读全文
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In English, we have a concept called root, which can be followed by some other words to form another longer word - let's call this word successor. For 阅读全文
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Given a string, your task is to count how many palindromic substrings in this string. The substrings with different start indexes or end indexes are c 阅读全文
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You are given n pairs of numbers. In every pair, the first number is always smaller than the second number. Now, we define a pair (c, d) can follow an 阅读全文
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Solve a given equation and return the value of x in the form of string "x=#value". The equation contains only '+', '-' operation, the variable x and i 阅读全文
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The set S originally contains numbers from 1 to n. But unfortunately, due to the data error, one of the numbers in the set got duplicated to another n 阅读全文
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Given an array consisting of n integers, find the contiguous subarray of given length k that has the maximum average value. And you need to output the 阅读全文
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A message containing letters from A-Z is being encoded to numbers using the following mapping way: Beyond that, now the encoded string can also contai 阅读全文
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In LeetCode Store, there are n items to sell. Each item has a price. However, there are some special offers, and a special offer consists of one or mo 阅读全文
