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On an 8x8 chessboard, there can be multiple Black Queens and one White King. Given an array of integer coordinates queens that represents the position 阅读全文
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Balanced strings are those that have an equal quantity of 'L' and 'R' characters. Given a balanced string s, split it in the maximum amount of balance 阅读全文
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Given an integer n, your task is to count how many strings of length n can be formed under the following rules: Each character is a lower case vowel ( 阅读全文
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In a gold mine grid of size m x n, each cell in this mine has an integer representing the amount of gold in that cell, 0 if it is empty. Return the ma 阅读全文
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When use the VsVim plugin in Visual Studio for Mac and type the closing part of a parenthesis, you might see ClosePair(')') pop up with awkward sound. 阅读全文
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Given an integer array arr and an integer difference, return the length of the longest subsequence in arr which is an arithmetic sequence such that th 阅读全文
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We have n chips, where the position of the ith chip is position[i]. We need to move all the chips to the same position. In one step, we can change the 阅读全文
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In an n*n grid, there is a snake that spans 2 cells and starts moving from the top left corner at (0, 0) and (0, 1). The grid has empty cells represen 阅读全文
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You are given a string s and an integer k, a k duplicate removal consists of choosing k adjacent and equal letters from s and removing them, causing t 阅读全文
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There is Client-Side Library under the Add when I right click the project on Visual Studio for Mac. So I searched on Google, and find this post LibMan 阅读全文
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You are given two strings s and t of the same length. You want to change s to t. Changing the i-th character of s to i-th character of t costs |s[i] - 阅读全文
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Given an array of integers arr, write a function that returns true if and only if the number of occurrences of each value in the array is unique. Exam 阅读全文
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Design a Skiplist without using any built-in libraries. A skiplist is a data structure that takes O(log(n)) time to add, erase and search. Comparing w 阅读全文
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There are n items each belonging to zero or one of m groups where group[i] is the group that the i-th item belongs to and it's equal to -1 if the i-th 阅读全文
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You are given a string s, and an array of pairs of indices in the string pairs where pairs[i] = [a, b] indicates 2 indices(0-indexed) of the string. Y 阅读全文
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An ugly number is a positive integer that is divisible by a, b, or c. Given four integers n, a, b, and c, return the nth ugly number. Example 1: Input 阅读全文
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Given an array of distinct integers arr, find all pairs of elements with the minimum absolute difference of any two elements. Return a list of pairs i 阅读全文
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There are n servers numbered from 0 to n - 1 connected by undirected server-to-server connections forming a network where connections[i] = [ai, bi] re 阅读全文
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Given an integer array arr and an integer k, modify the array by repeating it k times. For example, if arr = [1, 2] and k = 3 then the modified array 阅读全文
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You are given a string s that consists of lower case English letters and brackets. Reverse the strings in each pair of matching parentheses, starting 阅读全文
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Given a string text, you want to use the characters of text to form as many instances of the word "balloon" as possible. You can use each character in 阅读全文
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Given two integer arrays arr1 and arr2, return the minimum number of operations (possibly zero) needed to make arr1 strictly increasing. In one operat 阅读全文
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Given an array of integers, return the maximum sum for a non-empty subarray (contiguous elements) with at most one element deletion. In other words, y 阅读全文
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Given a date, return the corresponding day of the week for that date. The input is given as three integers representing the day, month and year respec 阅读全文
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A bus has n stops numbered from 0 to n - 1 that form a circle. We know the distance between all pairs of neighboring stops where distance[i] is the di 阅读全文
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With respect to a given puzzle string, a word is valid if both the following conditions are satisfied: word contains the first letter of puzzle. For e 阅读全文
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Given a string s, we make queries on substrings of s. For each query queries[i] = [left, right, k], we may rearrange the substring s[left], ..., s[rig 阅读全文
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Return the number of permutations of 1 to n so that prime numbers are at prime indices (1-indexed.) (Recall that an integer is prime if and only if it 阅读全文
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You have an infinite number of stacks arranged in a row and numbered (left to right) from 0, each of the stacks has the same maximum capacity. Impleme 阅读全文
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Given the head of a linked list, we repeatedly delete consecutive sequences of nodes that sum to 0 until there are no such sequences. After doing so, 阅读全文
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Let the function f(s) be the frequency of the lexicographically smallest character in a non-empty string s. For example, if s = "dcce" then f(s) = 2 b 阅读全文
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A transaction is possibly invalid if: the amount exceeds $1000, or; if it occurs within (and including) 60 minutes of another transaction with the sam 阅读全文
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Given a string s, return the last substring of s in lexicographical order. Example 1: Input: s = "abab" Output: "bab" Explanation: The substrings are 阅读全文
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Given an n x n grid containing only values 0 and 1, where 0 represents water and 1 represents land, find a water cell such that its distance to the ne 阅读全文
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Given the root of a binary tree, the level of its root is 1, the level of its children is 2, and so on. Return the smallest level x such that the sum 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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Design a data structure that efficiently finds the majority element of a given subarray. The majority element of a subarray is an element that occurs 阅读全文
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Given a string text, we are allowed to swap two of the characters in the string. Find the length of the longest substring with repeated characters. Ex 阅读全文
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You have d dice and each die has f faces numbered 1, 2, ..., f. Return the number of possible ways (out of fd total ways) modulo 109 + 7 to roll the d 阅读全文
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Given a string date representing a Gregorian calendar date formatted as YYYY-MM-DD, return the day number of the year. Example 1: Input: date = "2019- 阅读全文
