Articles
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463 - Island Perimeter
You are given a map in form of a two-dimensional integer grid where 1 represents land and 0 represents water. Grid cells are connected horizontally/vertically (not diagonally). The grid is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells). The island doesn’t have “lakes” (water inside that isn’t connected to the water around the island). One cell is a square with side length 1. The grid is rectangular, width and height don’t exceed 100. Determine the perimeter of the island.
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Reverse String
Write a function that takes a string as input and returns the string reversed.
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496 - Next Greater Element I
You are given two arrays (without duplicates) nums1 and nums2 where nums1’s elements are subset of nums2. Find all the next greater numbers for nums1’s elements in the corresponding places of nums2. The Next Greater Number of a number x in nums1 is the first greater number to its right in nums2. If it does not exist, output -1 for this number.
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Reshape the Matrix
In MATLAB, there is a very useful function called ‘reshape’, which can reshape a matrix into a new one with different size but keep its original data. You’re given a matrix represented by a two-dimensional array, and two positive integers r and c representing the row number and column number of the wanted reshaped matrix, respectively. The reshaped matrix need to be filled with all the elements of the original matrix in the same row-traversing order as they were. If the ‘reshape’ operation with given parameters is possible and legal, output the new reshaped matrix; Otherwise, output the original matrix.
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476 - Number Complement
Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.
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Keyboard Row
Given a List of words, return the words that can be typed using letters of alphabet on only one row’s of American keyboard like the image below.
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Reverse Words in a String III
Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.
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461 - Hamming Distance
The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Given two integers x and y, calculate the Hamming distance.
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561 - Array Partition 1
Given an array of 2n integers, your task is to group these integers into n pairs of integer, say (a1, b1), (a2, b2), …, (an, bn) which makes sum of min(ai, bi) for all i from 1 to n as large as possible.
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Beautiful Soup Cheat Sheet
Beautiful Soup Cheat Sheet
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507 - Perfect number
We define the Perfect Number is a positive integer that is equal to the sum of all its positive divisors except itself. Now, given an integer n, write a function that returns true when it is a perfect number and false when it is not.
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Add google analytics to your website
Add google analytics to your website
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HTML Tags
Useful Html tags
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501 - Find Mode in Binary Search Tree
Given a binary search tree (BST) with duplicates, find all the mode(s) (the most frequently occurred element) in the given BST.
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Build crawler using scrapy
Build crawler using scrapy
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Docker cheat sheet
Docker cheet sheet
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Deep Learning Notes
Deep learning notes
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Python notes
Python notes
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333 - Largest BST Subtree
Given a binary tree, find the largest subtree which is a Binary Search Tree (BST), where largest means subtree with largest number of nodes in it.
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331 - Verify Preorder Serialization of a Binary Tree
Given a string of comma separated values, verify whether it is a correct preorder traversal serialization of a binary tree. Find an algorithm without reconstructing the tree.
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334 - Increasing Triplet Subsequence
Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array.
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332 - Reconstruct Itinerary
Given a list of airline tickets represented by pairs of departure and arrival airports [from, to], reconstruct the itinerary in order. All of the tickets belong to a man who departs from JFK. Thus, the itinerary must begin with JFK.
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330 - Patching Array
Given a sorted positive integer array nums and an integer n, add/patch elements to the array such that any number in range [1, n] inclusive can be formed by the sum of some elements in the array. Return the minimum number of patches required.
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Find the difference between two set
找出两个数组的差，比如A = [1,1,1,2,2,2], B = [2,2,3]，在A出现在B不出现的集合是[1,1,1,2]
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360 - Sort Transformed Array
Given an equation y = ax^2 + bx + c, and sorted array X, output sorted Y.
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Longest Increasing Path in a Matrix
Given an integer matrix, find the length of the longest increasing path. From each cell, you can either move to four directions: left, right, up or down. You may NOT move diagonally or move outside of the boundary (i.e. wrap-around is not allowed).
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Top k elements with most occurrences
Find k elements within a array with most occurrences.
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328 - Odd Even Linked List
Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes. You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity.
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327 - Count of Range Sum
Given an integer array nums, return the number of range sums that lie in [lower, upper] inclusive. Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j), inclusive.
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Pick a random number from a BST
Randomly pick a number from binary searach tree
