Find GCD of Two Numbers using Recursion – Java Code

Write a Java program to find GCD of two numbers using Recursion. Given two input integers, we have to write a code to find GCD of two numbers using recursion. For this program, I assume you are familiar with the concept of recursion. If you don’t know about recursion then check my previous post on recursion vs iteration.

Java Program to Find the First Non-repeated Character in a String

Write a java program to find the first non-repeated character in a string.Given an input string, we have to write a java code to find the first non-repeated character in a string.

For example –

i) Input string – java
Output – j (j is the first non-repeating character in a string)

ii) Input string – web rewrite
Output – b (b is the first non-repeating character in a string)

Check whether Two Strings are Anagrams of each other

Write a program to check whether two strings are anagrams of each other.

What is an Anagram ?

Two strings are said to be anagrams of each other if it contains the same characters, only the order of characters in both the strings is different. In other words, both strings must contain the same exact letters in the same exact frequency.

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.

Recursion vs Iteration – Difference between Recursion and Iteration

Recursion vs Iteration. What’s the difference between recursion and iteration. Recursion and Iteration both are two different programming approaches. In some cases recursion is best suited and in some other cases iterative way of programming is good.

In programming, repeated set of instructions can be handled either by using recursive or iterative approach in your code. So which approach you choose and why. Let’s talk about recursion vs iteration.

Implementation of Binary Search using Recursion.

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.