Articles
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539 - Minimum Time Difference
Given a list of 24-hour clock time points in “Hour:Minutes” format, find the minimum minutes difference between any two time points in the list.
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609 - Find Duplicate File In System
```python from collections import defaultdict class Solution: def findDuplicate(self, paths: List[str]) -> List[List[str]]: if not paths: return []
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953 - Verifying An Alien Dictionary
In an alien language, surprisingly they also use english lowercase letters, but possibly in a different order. The order of the alphabet is some permutation of lowercase letters. Given a sequence of words written in the alien language, and the order of the alphabet, return true if and only if the given words are sorted lexicographicaly in this alien language.
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560 - Subarray Sum Equals K
Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k.
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1007 - Minmum Domino Rotations For Equal Row
In a row of dominoes, A[i] and B[i] represent the top and bottom halves of the i-th domino. (A domino is a tile with two numbers from 1 to 6 - one on each half of the tile.) We may rotate the i-th domino, so that A[i] and B[i] swap values. Return the minimum number of rotations so that all the values in A are the same, or all the values in B are the same. If it cannot be done, return -1.
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347 - Top K Frequent Elements
Given a non-empty array of integers, return the k most frequent elements.
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1268 - Search Suggestions System
Given an array of strings products and a string searchWord. We want to design a system that suggests at most three product names from products after each character of searchWord is typed. Suggested products should have common prefix with the searchWord. If there are more than three products with a common prefix return the three lexicographically minimums products. Return list of lists of the suggested products after each character of searchWord is typed.
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994 - Rotting Oranges
In a given grid, each cell can have one of three values:
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937 - Reorder Data in Log Files
You have an array of logs. Each log is a space delimited string of words. For each log, the first word in each log is an alphanumeric identifier. Then, either:
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766 - Toeplitz Matrix
A matrix is Toeplitz if every diagonal from top-left to bottom-right has the same element. Now given an M x N matrix, return True if and only if the matrix is Toeplitz.
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734 - Sentence Similarity
Given two sentences words1, words2 (each represented as an array of strings), and a list of similar word pairs pairs, determine if two sentences are similar. Note that the similarity relation is not transitive. For example, if “great” and “fine” are similar, and “fine” and “good” are similar, “great” and “good” are not necessarily similar.
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737 - Sentence Similarity II
Given two sentences words1, words2 (each represented as an array of strings), and a list of similar word pairs pairs, determine if two sentences are similar.
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418 - Sentence Screen Fitting
Given a rows x cols screen and a sentence represented by a list of non-empty words, find how many times the given sentence can be fitted on the screen.
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686 - Repeated String Match
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.
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406 - Queue Reconstruction By Height
Suppose you have a random list of people standing in a queue. Each person is described by a pair of integers (h, k), where h is the height of the person and k is the number of people in front of this person who have a height greater than or equal to h. Write an algorithm to reconstruct the queue.
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417 - Pacific Atlantic Water Flow
Given an m x n matrix of non-negative integers representing the height of each unit cell in a continent, the “Pacific ocean” touches the left and top edges of the matrix and the “Atlantic ocean” touches the right and bottom edges. Water can only flow in four directions (up, down, left, or right) from a cell to another one with height equal or lower. Find the list of grid coordinates where water can flow to both the Pacific and Atlantic ocean.
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681 - Next Closest Time
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 can be reused. You may assume the given input string is always valid. For example, “01:34”, “12:09” are all valid. “1:34”, “12:9” are all invalid.
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524 - Longest Word In Dictionary Through Deleting
Given a string and a string dictionary, find the longest string in the dictionary that can be formed by deleting some characters of the given string. If there are more than one possible results, return the longest word with the smallest lexicographical order. If there is no possible result, return the empty string.
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687 - Longest Univalue Path
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 root.
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482 - License Key Formatting
You are given a license key represented as a string S which consists only alphanumeric character and dashes. The string is separated into N+1 groups by N dashes. Given a number K, we would want to reformat the strings such that each group contains exactly K characters, except for the first group which could be shorter than K, but still must contain at least one character. Furthermore, there must be a dash inserted between two groups and all lowercase letters should be converted to uppercase. Given a non-empty string S and a number K, format the string according to the rules described above.
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616 - Add Bold Tag In String
Given a string s and a list of strings dict, you need to add a closed pair of bold tag and to wrap the substrings in s that exist in dict. If two such substrings overlap, you need to wrap them together by only one pair of closed bold tag. Also, if two substrings wrapped by bold tags are consecutive, you need to combine them.
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354 - Russian Doll Envelopes
You have a number of envelopes with widths and heights given as a pair of integers (w, h). One envelope can fit into another if and only if both the width and height of one envelope is greater than the width and height of the other envelope. What is the maximum number of envelopes can you Russian doll? (put one inside other)
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370 - Range Addition
Assume you have an array of length n initialized with all 0’s and are given k update operations. Each operation is represented as a triplet: [startIndex, endIndex, inc] which increments each element of subarray A[startIndex … endIndex] (startIndex and endIndex inclusive) with inc. Return the modified array after all k operations were executed.
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369 - Plus One Linked List
Given a non-negative integer represented as non-empty a singly linked list of digits, plus one to the integer. You may assume the integer do not contain any leading zero, except the number 0 itself. The digits are stored such that the most significant digit is at the head of the list.
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359 - Logger Rate Limiter
Design a logger system that receive stream of messages along with its timestamps, each message should be printed if and only if it is not printed in the last 10 seconds. Given a message and a timestamp (in seconds granularity), return true if the message should be printed in the given timestamp, otherwise returns false.
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356 - Line Reflection
Given n points on a 2D plane, find if there is such a line parallel to y-axis that reflect the given set of points.
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353 - Design Snake Game
Design a Snake game that is played on a device with screen size = width x height. Play the game online if you are not familiar with the game. The snake is initially positioned at the top left corner (0,0) with length = 1 unit. You are given a list of food’s positions in row-column order. When a snake eats the food, its length and the game’s score both increase by 1. Each food appears one by one on the screen. For example, the second food will not appear until the first food was eaten by the snake. When a food does appear on the screen, it is guaranteed that it will not appear on a block occupied by the snake.
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351 - Android Unlock Patterns
Given an Android 3x3 key lock screen and two integers m and n, where 1 ≤ m ≤ n ≤ 9, count the total number of unlock patterns of the Android lock screen, which consist of minimum of m keys and maximum n keys.
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503 - Next Greater Element II
Given a circular array (the next element of the last element is the first element of the array), print the Next Greater Number for every element. The Next Greater Number of a number x is the first greater number to its traversing-order next in the array, which means you could search circularly to find its next greater number. If it doesn’t exist, output -1 for this number.
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487 - Max Consecutive Ones II
Given a binary array, find the maximum number of consecutive 1s in this array if you can flip at most one 0.
