## Find Intersection of Two Arrays – Java Code

Given two sorted arrays, Write a java code to find intersection of two arrays.

For example, if the input arrays are:

arr1[] = {2, 3, 6, 7, 9, 11}
arr2[] = {4, 6, 8, 9, 12}

Then your program should print intersection as {6, 9}. Before writing actual code, let’s first discuss different approaches to solve this problem.

## Move All Zeroes to End of Array – Java Code

Write a java program to move all zeroes to end of array. Given an array of random integers move all zeroes to end of array. The order of all other elements of an array should be same.

In this tutorial, We are going to discuss and write a java program to move zeroes to end of an array. It is another interesting problem which generally asked in a technical interviews.

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For example –

Input : {1, 2, 0, 4, 0, 5, 3, 8}

Output: {1, 2, 4, 5, 3, 8, 0, 0}

You can see in the example, we have moved zeroes to the end of an array.

## Java Program to Add Two Matrices

Write a java program to add two matrices.

For example : Given two matrices A and B the sum of these two matrices is A + B.

{1,  5,  1}                   {1,  1,  9}              {2,  6,  10}
{2,  8,  2}      +         {2,  2,  3}    =       {4,  10,  5}
{3,  7,  1}                  {5,  6,  4}              {8,  13,  5}

## Java Program to Calculate Power of a Number

In this tutorial, I am going to explain how to calculate power of a number without using Math.pow method in java.

For example:

i) 23 = 8 (2 * 2 * 2)
ii) 52 = 25 (5 * 5)

## Insertion Sort Program in Java

Insertion Sort Program in Java. Write a java program to sort an unsorted array using insertion sort.

In this tutorial, We are going to cover following points.

• How insertion sort works?
• Insertion sort program in java.
• Video tutorial which explain insertion sort algorithm.

Let’s say we have an unsorted array and we want to sort this array using insertion sort. Let’s first understand how insertion sort works?

Input : {5, 4, 2, 9, 1}

Output : {1, 2, 4, 5, 9}

## Find Sum of Digits of a Number – Java Code

Write a java program to find sum of digits of a number. Given an input number, we have to write a java code to calculate sum of digits of a number.

For example –

i)

Input : 256

Output : 13 (2+5+60

ii)

Input : 15

Output : 6 (1+5)

## How to Convert Decimal to Binary Number – Java Code

Given a  decimal  number, Write a java program to convert decimal to binary number.

For example :

Input : 4 ,   Output : 100

Input : 5 ,    Output : 101

Input : 10 ,    Output : 1010

## Find Next Greater Element in an Array – Java Code

Write a java program to find next greater element in an array. Given an input array, find the next greater element for every element of an array.The next greater element x is the first greater element on the right side of x in an array.

In this tutorial, I am going to explain two approaches and their time complexities to solve this problem. In the first approach, we’ll see how we can find next greater element using two for loops. And after that we can discuss how we can find next greater element using stack.

Also, I have explained how to find next greater element using stack through video tutorial.

For example:

Let’s take an array: [4, 2, 6, 8, 1]

4 => 6 (First next greater element of 4 is 6)
2 => 6 (Next greater element of 2 is 6)
6 => 8 (Next greater element of 6 is 8)
8 => null
1 => null

## Find Second Smallest Number in an Array : Java Code

Write a java program to find second smallest number in an array. Given an input array, write a java code to print second smallest number of an array.

For example :

arr = {-1, 7, 1, 34, 18}

The second smallest number in this array is 1.

## Java Program to Reverse a String using Recursion

Write a java program to reverse a string using recursion. In this tutorial, I am going to explain how to write a java code which reverse an input string using recursion. I have also added the video at the end of this tutorial.

For example :

Input String: Object
Output String: tcejbO