How to Check if a Number is a Power of 2

How to check if a number is a power of 2.  To understand this question, let’s take some example.

Example –

Input – 16   – 16 is a power of 2 (2^4).

Input – 15 – 15 is not a power of 2.

Input – 32- 32 is a power of 2 (2^5).

We can use multiple approaches to check whether a number is a power of 2 or not.

Find First and Last Position of a Number in a Sorted Array – Java Code

Given a sorted array which contains duplicate elements, we have to write a java code to find first and last position of a number in a sorted array. Given a number x, write a code to find it’s first and last index in an array.

For example –

Subscribe Our Tutorials

Get Latest Updates on Facebook

Suppose the input array is arr[] : {1, 4, 7, 8, 8, 11, 11, 11, 11, 12, 13, 13} and number to searched is 11 then the first index of 11 is 5 and last index is 8.

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. In this tutorial, We are going to discuss another interesting problem which generally asked in an technical interviews.

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

For example, if a given array is {1, 2, 0, 4, 0, 5, 3, 8}, than the output should be {1, 2, 4, 5, 3, 8, 0, 0}.

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.

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

Java Program to Find Missing Number in Array

Write a java program to find missing number in array. Given an array of n-1 integers and these integers are in the range of 1 to n. One of the integer is missing from an array. We have to write an efficient java code to find missing number from an array. An array does not contains any duplicates.