Question

Write a method swapArrayEnds() that swaps the first and last elements of its array parameter. Ex: sortArray = {10, 20, 30, 40} becomes {40, 20, 30, 10}.

Answer 1

Answer:

Python method swapArrayEnds()

def swapArrayEnds(array):      

   size = len(array)  

   temp = array[0]  

   array[0] = array[size - 1]  

   array[size - 1] = temp  

   return array

         

Explanation:

You can call the method in main program to swap the first and last elements of sortArray as following:

def swapArrayEnds(array):

   size = len(array)  

   temp = array[0]  

   array[0] = array[size - 1]  

   array[size - 1] = temp  

   return array  

     

sortArray = [10, 20, 30, 40]  

 

print(swapArrayEnds(sortArray))

This function works as following:

size stores the length of the array.

temp is a temporary variable that holds the first element of the array

The it swaps the first element of the array with the last element using this statement: array[0] = array[size - 1]  where size-1 contains the last element.

It finally stores the last element of the array in temp and returns the array after this swapping is done.

Then in the main program an array sortArray is given the values 10,20,30,40 and then the method swapArrayEnds()  is called to swap the first and last elements of sortArray.

The complete program with the output is attached in a screenshot.

Answer 2

Answer:

The solution code is written in Java.

1.    public static void swapArrayEnds(int myArray[]){
2.        int lastIndex = myArray.length-1;
3.        int temp = myArray[0];
4.        myArray[0] = myArray[lastIndex];
5.        myArray[lastIndex ] = temp;
6.    }

Explanation:

First create the swapArrayEngs method that take one input array parameter (Line 1).

Since we need to swap the first and last element of the array, we need to get the first index and last index of the array. The first index is 0 and the last index can be calculated by subtracting the length of array from 1 (Line 2).

Next, we can create a temp variable to hold the value of the first element (Line 3). Then we use the lastIndex the get the value of last element and assign it to the first element of array (Line 4). Lastly, we assign the temp (holding the  initial first element value) to the last element of array (Line 5).