Java Program to Check Prime Number

Write a Java program to check prime number. Given an input integer, We have to write an efficient code to check whether a number is prime or not.

Before writing a program, let’s quickly understand what is a prime number.

Prime Number

A prime number is a number that is greater than 1 and it has no positive divisors other than 1 and itself.

For example – 3, 13, 7  is a prime number, as it’s divisible by 1 and itself. Similarly, 29, 19 etc. are also prime numbers.

6 is not a prime number as it’s divisible by 1, 2, 3 and 6.

 2 is the only even prime number.

 

How to check whether a number is prime or not in Java

Program to Print Factorial of a Number in PHP – Iterative & Recursive Approach

Write a program to print factorial of a number in PHP. In this tutorial, We are going to write a PHP code to print factorial of a number using iterative as well as recursive approach. Before solving this problem let’s understand what is factorial.

Program to Print Factorial of a Number in PHP

Program to Print Factorial of a Number in PHP

Find Common Elements in Two Arrays – Intersection of two Arrays

Given two sorted arrays, Write a code to find common elements in two arrays. In other words, we have to write a code to find the intersection of two arrays.

Find Common Elements in Two Arrays

Let’s assume following two sorted arrays arr1[] and arr2[].

int arr1[] = {2,  3,  4,  5,  6};
int arr2[] = {4,  6,  7,  8,  9};

So the common elements in these two arrays is 4 and 6.

Generate Prime Numbers between 1 to N – Sieve of Eratosthenes

Write an efficient program to generate prime numbers between 1 to N (Where N is 10, 100, 1000 etc). This question can also be asked like this, Generate prime numbers between 1 to 100 or 1 to 10 etc.

Suppose the value of N is 10, So the prime numbers between 1 to 10 is 2, 3, 5, 7.  Now let’s learn the most efficient algorithm (Sieve of Eratosthenes) to generate Prime Numbers between 1 to N. Before solving this program, let’s understand what is a prime number.

MCQ on Data Structure – Stack and Queue

MCQ on stack and queue data structure. The concept of Stack and Queue data structure is very important in computer science. In my previous post i have discussed following things.

Stack program in C using Array.

Queue data structure and their implementation.

The purpose of this objective questions is to test how well you understand the concept of stack and queue.

Program to Search an Element in an Array

Write a program to search an element in an array. Given a sorted array, how do you search an element in an array. Think for a moment how do you solve this problem.

You can use multiple approaches to find the solution of this problem. But try to solve this problem in minimum time complexity.

Find the Second Largest Number in an Array

Write a program to find the second largest number in an array. Given an unsorted array, we have to write a code to find the second largest number in an array. Also, we need to focus on time complexity. As the time complexity of an algorithm is very important in terms of an interview.

For example – Let’s take an array.

Input – arr[] = { 4, 1, 5, 2, 8, 0, 3, 55}

Output – 8

The second largest element in this array is 8.  Think for a moment, how do you find the second largest number in an array?  There are multiple ways to solve this problem. Which approach you prefer and why?

In this tutorial, we cover following things –

  • How to find the second largest number in an array using sorting.
  • C program to find the second largest number in an array.
  • C++ program to find the second largest number in an array.
  • PHP code to find the second largest number in an array.
  • Java code to find the second largest number in an array.