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摘要： Happy NumberWrite an algorithm to determine if a number is happy.A happy number is a number defined by the following process: Starting with any positi... 阅读全文

摘要： 3SumGiven an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum... 阅读全文

摘要： 4SumGiven an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target?Find all unique quadruplets in the array w... 阅读全文

摘要： Two SumGiven an array of integers, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the... 阅读全文

摘要： Divide Two IntegersDivide two integers without using multiplication, division and mod operator.If it is overflow, return 2147483647ExampleGiven divide... 阅读全文

摘要： Count of Smaller NumberGive you an integer array (index from 0 to n-1, where n is the size of this array, value from 0 to 10000) and an query list. Fo... 阅读全文

摘要： Intersection of Two Linked ListsWrite a program to find the node at which the intersection of two singly linked lists begins.ExampleThe following two ... 阅读全文

摘要： Find the Missing NumberGiven an array contains N numbers of 0 .. N, find which number doesn't exist in the array.ExampleGiven N = 3 and the array [0, ... 阅读全文

摘要： Palindrome Linked ListImplement a function to check if a linked list is a palindrome.ExampleGiven 1->2->1, return trueChallengeCould you do it in O(n)... 阅读全文

摘要： Search a 2D MatrixWrite an efficient algorithm that searches for a value in an m x n matrix.This matrix has the following properties:Integers in each ... 阅读全文