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All posts in Algorithms

Add Two Numbers

Problem Statement You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list. You may assume the two numbers do not contain any . . . Read more

Two Sum

Problem Statement Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. Example Given nums = [2, 7, 11, 15], . . . Read more

Currency Convert

Problem Statement Given the following input CSV file: From To Rate USD;EUR;0.89 USD;GBP;0.79 GBP;CHF;1.26 CHF;JPY;108.66 … … … Implement an algorithm to convert from a source currency to a target currency. package problems; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.util.*; /** * Given the following input CSV file: * * From . . . Read more

Triple Sum

Problem Statement Given arrays of different sizes, find the number of distinct triplets where is an element of , written as , , and , satisfying the criteria: and For example, given and we find four distinct triplets: Function Description Complete the triplets function in the editor below. It must . . . Read more


Problem Statement In this challenge, you will be given an array of integers, each unique within the array, and an integer representing a target difference. Determine the number of pairs of elements in the array that have a difference equal to the target difference. For example, consider the array [1, . . . Read more

Ice Cream Parlor

Problem Statement Each time Sunny and Johnny take a trip to the Ice Cream Parlor, they pool their money to buy ice cream. On any given day, the parlor offers a line of flavors. Each flavor has a cost associated with it. Given the value of and the of each . . . Read more

Strokes to paint

Problem Statement Alex wants to paint a picture but hates taking the brush off the canvas. In one stroke, Alex can only paint the same colored cells which are joined via some edge. Given the painting, determine the minimum number of strokes to completely paint the picture. Take for example, . . . Read more

Better Compression

Problem Statement Consider a string, S, that is a series of characters, each followed by its frequency as an integer. The string is not compressed correctly, so there may be many occurrences of the same character. A properly compressed string will consist of one instance of each character in alphabetical . . . Read more

Mud Walls

Problem Statement A child likes to build mud walls by placing mud between sticks positioned on a number line. The gap between sticks will be referred to as a cell, and each cell will contain one segment of wall. The height of mud in a segment cannot exceed 1 unit . . . Read more

Weird Faculty

Problem Statement This semester you are taking a course taught by a faculty member who has a weird way of grading tests. In a test, n questions will be asked, and the correctness of the answers is already determined. For the ith question, the verdict will be v[i] (where 0 . . . Read more