Duplicate even elements in an array

Given an array of numbers, write a program to duplicate the even numbers and return the new array. Example: Input: [2, 4, 1, 5, 2, 3, 8, 9, 10, 4] Output: [2, 2, 4, 4, 1, 5, 2, 2, 3, 8, 8, 9, 10, 10, 4, 4] Input: [2, 4, 6, 8] Output: [2, 2, … Read more

Find the number of pairs with odd XOR

Given an array of integers, write a program to find the number of pairs for which the XOR is an odd number. Example: Input[] = {3, 2, 1} Output: 2 Note: 1 XOR 2 = 3 and 2 XOR 3 = 1 Input[] = {3, 6, 9, 4} Output: 4 Naive Approach: Use nested loops … Read more

Count number of pairs which has sum equal to K

Given an array of integers and number K, write a program to find the number of pairs which has sum equal to K. Example: int input [] = {6, 3, 2, 9, 2, 2, 2, 1} int K = 4 Output: 7 int input [] = {5, 5, 5, 5} int K = 10 Output: … Read more

Count similar words in a given array

Given an array of strings, write a program to count all the similar words.  Similar words: Two words are similar if Has spaces in-between or at the end. Ex: “Apple” and ” A pp le” are similar. Has upper or lower cases. Ex: “APPle” and “apple” are similar. Has special characters. Ex: “app%^L&e” and “@@apple” … Read more

Number of Contiguous Parking Areas

Problem: Given a building with parking slots. If a spot is free then it is marked by 1 and if the spot is taken by a vehicle then it is marked by 0. Write a program to find the number of free contiguous parking areas in the building. One free parking area can have one … Read more

The largest number can be formed from the given number

Given a number write an algorithm to construct the largest number possible by using the digits of given number. Given number could be a negative number as well.  Example: Given Input: 34277765 Output: 77765432 Given Input: -342765 Output: -234567 Given Input: 0 Output: 0 Given Input: 2034 Output: 4320 Approach: Sorting Check if the given … Read more

Print all nested directories and files in a given directory – Recursion

Given a source directory, write a recursive program to print all the nested directories and files in the source directory. Example: [Hellojava] [target] original-Hellojava-1.0-SNAPSHOT.jar [classes] [com] [example] [lambda] [demo] Hello.class [maven-archiver] pom.properties Hellojava-1.0-SNAPSHOT.jar pom.xml Hellojava.iml [src] [test] [java] [main] [resources] [java] [com] Hello.java Approach: Check if given file is directory,  if yes then print its … Read more

Maximum meetings in one room

You have one meeting room at your company. There are N meeting needs to take place. Every meeting has a start time and end time along with the meeting title. Your task is to schedule as many meetings as possible in that conference room with no conflicts.  Example: Meetings: A[ Start Time: 1, End Time: … Read more

Check if given sudoku is valid or not

Problem: Given a filled sudoku, write a program to check if sudoku is valid or following all of its rules. SUDOKU rules:  Each column contains all of the digits from 1 to 9 only once. Each row contains all of the digits from 1 to 9 only once. Each of the nine 3×3 sub-grid contains … Read more

Construct the Largest number from the given digits

Given a set of digits, write an algorithm to construct the largest number possible by appending the given digits. Example: Given Digits: [9, 1, 9, 2, 8, 4, 2] largest number: 9984221 Given Digits: [1, 2, 5, 6, 7] largest number: 76521 Approach: Sorting Sort the given array in descending order. Initialize result = 0. … Read more

Efficient Robot Problem – Find Minimum Trips

Problem: There is N number of items that need to be transferred from one place to another by a robot. Each item has a specific weight. The robot can carry maximum weight K in one trip. You need to come up with an algorithm to find out the minimum number of trips that the robot … Read more

Given an array, count the number of pairs with a given sum.

Objective: Given an array of integers, write a program to count all the pairs with the given sum. Example: Given array: [1, 5, 7, 1, -1], Sum= 6 Total Pairs: 3 Note: pairs are (1, 5), (5, 1) and (7, -1) Given array: [4, 5, 1, 2, 9, -2, -4], Sum= 5 Total Pairs: 2 … Read more

Two Sum Problem

Objective: Given an array of integers, and k. Write a program to find indexes of two elements in an array which sum is equal to K. Example: Given array: [5, 4, 7, 3, 9, 2], Sum = 13 Output: Found indexes are: 4 and 1 Given array: [1, 2, 3, 4, 5], Sum = 9 … Read more

Find if any two intervals overlap in given intervals

Objective: Interval is defined as [start, end]- the start of an interval to the end of the interval. Given a list of Intervals. Your task is to check if any two intervals overlap. Example: Given Interval: [[1,5], [6,10], [12,15], [3,7]] Two intervals are present which intersect Given Interval: [[1,5], [6,10], [12,15]] No intervals overlasx Approach:  … Read more

Find all subsets of size K from a given number N (1 to N)

Objective: Given two integers N and K, Write an algorithm to find subsets of size K from the numbers 1 to N.  Example: N = 5 K = 3 Output: [1, 2, 3] [1, 2, 4] [1, 2, 5] [1, 3, 4] [1, 3, 5] [1, 4, 5] [2, 3, 4] [2, 3, 5] [2, … Read more