## Find First Non-repeating Character in a String – Java Code

Write a java program to find first non-repeating character in a string. Given an input string, Write a java code to find first non-repeating 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)

## PHP Code to Find Second Largest Number in Array

Write a PHP code to find second largest number in array. Given an unsorted array, we have to write a PHP program to find the second largest number in an array.

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Apart from solving this problem. We have to focus on time complexity. As the time complexity of an algorithm is very important in terms of an interview.

## Reverse a String in PHP without using strrev() Method

Write a script to reverse a string in PHP without using strrev() method. In PHP, we can reverse a string easily using strrev() method. But think how will you reverse a string without using an inbuilt strrev() method.

## Find Largest Sum Contiguous Subarray – Kadane’s algorithm

Write a program to find largest sum contiguous subarray. Given an array of N elements, find the maximum possible sum of a contiguous subarray. An array can contain both positive and negative values.

For example –

Let’s take an array whose values are { 1, 2, -5, 4, 3, 8 , 5 }

The maximum sum of a subarray in this array is 20.  And the subarray is (4, 3, 8, 5).

## 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.

## Check Prime Number in Java

How to check prime number in Java. In this tutorial, we are going to write a Java program to check whether a number is prime or not. Also In this tutorial, we’ll discuss multiple approaches and their time complexity to solve this problem.

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

### What is 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.

## Find Common Elements in Two Arrays – Intersection of two Arrays

Write a c program to find common elements in two arrays. Given two positive integer arrays arr1 and arr2 of lengths len1 and len2 we have to write a c code to find intersection of these two arrays. Both the arrays are sorted.

Let’s assume we have 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.

## C Program to Print Prime Numbers from 1 to N – Sieve of Eratosthenes

Write a c program to print prime numbers from 1 to N (where n is an integer). This question can also be asked like, print prime numbers from 1 to 100 in c. In this tutorial, we are going to use sieve algorithm to print prime numbers from 1 to N.

Suppose the value of N is 10, So the prime numbers between 1 to 10 is 2, 3, 5, 7.

Now, Let’s learn how to print prime numbers from to 1 to N using Sieve of Eratosthenes. Before solving this program, let’s understand what is a prime number.

## 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.