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Given a string path, where path[i] = 'N', 'S', 'E' or 'W', each representing moving one unit north, south, east, or west, respectively. You start at t 阅读全文
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Given the root of a perfect binary tree, reverse the node values at each odd level of the tree. For example, suppose the node values at level 3 are [2 阅读全文
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You are given a 0-indexed m x n binary matrix grid. A 0-indexed m x n difference matrix diff is created with the following procedure: Let the number o 阅读全文
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You are given a string s consisting of lowercase English letters, and you are allowed to perform operations on it. In one operation, you can replace a 阅读全文
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You are given a string num, representing a large integer. Return the largest-valued odd integer (as a string) that is a non-empty substring of num, or 阅读全文
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Hercy wants to save money for his first car. He puts money in the Leetcode bank every day. He starts by putting in $1 on Monday, the first day. Every 阅读全文
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You are given an integer n, the number of teams in a tournament that has strange rules: If the current number of teams is even, each team gets paired 阅读全文
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You are given a string num representing a large integer. An integer is good if it meets the following conditions: It is a substring of num with length 阅读全文
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On a 2D plane, there are n points with integer coordinates points[i] = [xi, yi]. Return the minimum time in seconds to visit all the points in the ord 阅读全文
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You are given an array of strings words and a string chars. A string is good if it can be formed by characters from chars (each character can only be 阅读全文
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You are given an integer array nums sorted in non-decreasing order. Build and return an integer array result with the same length as nums such that re 阅读全文
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You are given a binary matrix matrix of size m x n, and you are allowed to rearrange the columns of the matrix in any order. Return the area of the la 阅读全文
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Given a 2D integer array nums, return all elements of nums in diagonal order as shown in the below images. Example 1: Input: nums = [[1,2,3],[4,5,6],[ 阅读全文
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A sequence of numbers is called arithmetic if it consists of at least two elements, and the difference between every two consecutive elements is the s 阅读全文
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Given a 0-indexed integer array nums of size n and two integers lower and upper, return the number of fair pairs. A pair (i, j) is fair if: 0 <= i < j 阅读全文
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Given a 0-indexed integer array nums of length n and an integer target, return the number of pairs (i, j) where 0 <= i < j < n and nums[i] + nums[j] < 阅读全文
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HTML entity parser is the parser that takes HTML code as input and replace all the entities of the special characters by the characters itself. The sp 阅读全文
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A string s is called good if there are no two different characters in s that have the same frequency. Given a string s, return the minimum number of c 阅读全文
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You are given a 0-indexed integer array nums. The array nums is beautiful if: nums.length is even. nums[i] != nums[i + 1] for all i % 2 == 0. Note tha 阅读全文
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Given a 0-indexed string s, permute s to get a new string t such that: All consonants remain in their original places. More formally, if there is an i 阅读全文