# Category: Beginner

## Count Set bits in a given Number

Objective: Given a Number, find all the set bits in that number. Example: Number: 23 Set bits: 4 (10111) Number: 15 Set bits: 4 (1111) Number: 21 Set bits: 3 (10101) Approach: Check the...

## Check if array contains all unique or distinct numbers.

Objective: Given an array of integers, write a program to check if array contains all unique numbers. Example: Integer [] arrA = { 1, 2, 3, 6, 4, 9, 8}; Output: Array has all...

## Product of all Unique elements in a given array.

Objective: Given an array of integers which contains duplicates as well. Write a program to find the product of all unique elements in the array. This problem is also referred as find the product...

## Reverse a given number – Java Code

Objective: Given a number, write a java program to reverse a number Example: Given Number: 1234 Output: 4321 Given Number: 1020 Output: 201 Approach:  Using loop Keep divide the number by 10 and add...

## Check if given number is perfect square – O(√N) Solution

Objective: Given a number, write a program to check if given number is perfect sqaure. Example: N = 16 Output: True N = 32 Output: False Approach: Naive Approach: If N = 1 return...

## Find first three largest elements in a given array

Objective: Given an array of integers, write an algorithm to find the first three largest elements in the array. Example: Int [] a = { 6, 8, 1, 9, 2, 1, 10}; Output: 10,...

## Selection Sort – Java Implementation

What is Selection Sort?? Selection sort is a simple sorting algorithm that builds the sorted array one item at a time. This sorting is efficient for small data sets, not efficient for large data...

Sometimes we need to print the numbers with its sign irrespective of number is positive (+) or negative(-). Example: X = 5, print = +5 Y = -8, print = -8 Say we need...

## Valid Brackets – Part 2 | Stack Method

Objective: Given a string containing just the characters ( , ) determine if the input string is valid. Example: ()()(()(()))() valid: true )()()( valid: false ()()) valid: false Approach: Earlier we discussed the solution which keeps...

## Find the roots of Quadratic Equation – Java Program

Quadratic equation is in the form = ax2 + bx + c Discriminant (d) = b2 – 4ac Then roots are calculates using the equations below Root_1 =  (-b + √d)/2a Root_2 =  (-b...

## Given two strings validate the output string

Objective: Given two input strings and one output strings, validate if output string contains all the characters from both the input strings. Example: Input1 = “boy”, Input2 = “girl”, output = “gboilry” Result =...

## Find Largest and Smallest word in a given String

Objective: Given a String, write a program to find largest and smallest word in it. Example: Input String: test Smallest Word: test Largest Word: test —————— Input String: This problem is solved at Algorithms...

## Find two smallest elements in a given array

Objective: Given an array of integers, write an algorithm to find the two smallest elements in the array. Example: Int [] a = { 6, 8, 1, 9, 2, 10}; Output: 1, 2 Int...

## Front and Back Search in an Array

Objective: Given an unsorted array of numbers and a number ‘x’, write a java program to search the number ‘x’ in the array and return its index else return -1. Example: Int [] a...

## Print all Unique elements in a given array

Objective: Given an array of integers which contains duplicates as well. Write a program to print all unique elements in the array. This problem is also referred as print all distinct elements in the...