WAP to Swap Two Adjacent Elements in an Array

Swap Two Adjacent Elements in an Array: This Java program takes an input array containing integers and swaps adjacent elements to create a modified array. The program achieves this by iterating through the array with a step size of 2 (i.e., taking every second element), and for each pair of adjacent elements, it swaps their positions.

Swap Two Adjacent Elements in an Array

package com.softwaretestingo.interviewprograms;
public class InterviewPrograms33 
{
	/*
	 * Input array- {1,2,3,4,5} 
	 * Output array- {2,1,4,3,5}
	 */
	public static void main(String[] args) 
	{
		int[] arr = {1,2,3,4,5};
		int tmp=0;
		for(int i =1;i<arr.length;i+=2)
		{
			tmp=arr[i];
			arr[i]=arr[i-1];
			arr[i-1]=tmp;
		}
		for(int i:arr)
			System.out.print(i);
	}
}

Output

21435

Here’s a breakdown of the program:

1. Define the main method:
   • The entry point of the program is the main method.
2. Initialize the input array:
   • The input array arr is initialized with the values {1, 2, 3, 4, 5}.
3. Swap adjacent elements:
   • The program iterates through the array with a for loop, starting from index 1 (the second element) and incrementing by 2 at each step.
   • For each iteration, it takes the current element arr[i] and swaps its position with the previous element arr[i-1] using a temporary variable tmp.
4. Print the modified array:
   • After processing all elements of the array and performing the swaps, the program prints the modified array elements.

Overall, this program swaps adjacent elements of the input array to create a modified array. For the given input array {1, 2, 3, 4, 5}, the output will be {2, 1, 4, 3, 5}, where adjacent elements have been swapped. The program demonstrates basic array manipulation and a simple for loop to achieve this task.

Alternative Way 1:

This Java program takes an input array containing integers and swaps adjacent elements to create a modified array. The program achieves this using a for loop and conditional statements to handle arrays of even and odd lengths.

package com.softwaretestingo.interviewprograms;
import java.util.Arrays;
public class InterviewPrograms33_1 
{
	/*
	 * Input array- {1,2,3,4,5} 
	 * Output array- {2,1,4,3,5}
	 */
	public static void main(String[] args) 
	{
		int [] a = {1,2,3,4,5};
		if ( a.length % 2 == 1 )
		{ 
			for ( int i = 0 ; i<a.length-1; i=i+2) 
			{
				int temp= a[i];
				a[i]= a[i+1];
				a[i+1]=temp;
			}
		}
		else if (a.length%2==0) 
		{
			for (int i=0; i<a.length; i=i+2)
			{
				int temp= a[i];
				a[i] = a[i+1];
				a[i+1]= temp ;
			}
		}
		System.out.println(Arrays.toString(a));
	}
}

Output

[2, 1, 4, 3, 5]

Here’s a breakdown of the program:

1. Define the main method:
   • The entry point of the program is the main method.
2. Initialize the input array:
   • The input array a is initialized with the values {1, 2, 3, 4, 5}.
3. Swap adjacent elements for arrays with odd length:
   • The program first checks if the length of the array a is odd (i.e., a.length % 2 == 1).
   • If the array length is odd, it means the last element is not paired with another element for swapping, so it iterates through the array from the beginning to the second-to-last element using a for loop with a step size of 2.
   • For each iteration, it swaps the current element a[i] with the next element a[i+1] using a temporary variable temp.
4. Swap adjacent elements for arrays with even length:
   • If the array length is even (i.e., a.length % 2 == 0), it means all elements are paired for swapping, so it iterates through the array from the beginning to the last element using a for loop with a step size of 2.
   • It swaps the current element a[i] with the next element a[i+1] using a temporary variable temp.
5. Print the modified array:
   • After processing all elements and performing the swaps, the program prints the modified array using Arrays.toString(a).

Overall, this program swaps adjacent elements of the input array to create a modified array. For the given input array {1, 2, 3, 4, 5}, the output will be {2, 1, 4, 3, 5}, where adjacent elements have been swapped. The program demonstrates basic array manipulation, conditional statements, and loops to achieve this task.