Array reversal in c | step by step hackerrank solution

Hackerrank Solution - Array Reversal:

Welcome back, Guys!!

In this post, we will solve the Array Reversal  Hackerrank problem.

It is a medium level problem using the concept of Array and loops...

The problem Statement For Hackerrank Array Reversal problem is as follows :

Given an array, of size , reverse it.

Example: If array, , after reversing it, the array should be, .

Input Format

The first line contains an integer, n, denoting the size of the array. The next line contains n space-separated integers denoting the elements of the array.

Constraints

1<= n <= 1000

1<= arr_i <= 1000 , where arr_i is the i^th element of the array.

Output Format

The output is handled by the code given in the editor, which would print the array.

Sample Input 0

6

16 13 7 2 1 12

Sample Output 0

12 1 2 7 13 16

Explanation 0

Given array,  =[16, 13, 7 ,2, 1, 12] . After reversing the array,  = [12 ,1 ,2 ,7 ,13 ,16 ]

Sample Input 1

7

1 13 15 20 12 13 2

Sample Output 1

2 13 12 20 15 13 1

Sample Input 2

8

15 5 16 15 17 11 5 11

Sample Output 2

11 5 11 17 15 16 5 15

The solution code for Hackerrank Array Reversal problem is as follows :

Since arrays store there values in contagious memory location i.e one after the other . So to reverse the order of array, we should start from highest index (size -1) to lowest index (i.e 0).

#include <stdio.h>

#include <stdlib.h>

int main()

{

    int num, *arr, i;

    scanf("%d", &num);

    arr = (int*) malloc(num * sizeof(int));

//or u can also use 'int arr[num];'or calloc func

    for(i = 0; i < num; i++) {

        scanf("%d", arr + i);

    }

    /* Write the logic to reverse the array. */

/*

    for(i = num-1; i >= 0; i--)

        printf("%d ", *(arr + i));

it is wrong if you are doing this as you aren't reversing the array

*/

int s=0,e=n-1; while(s<e) { int t=a[s]; a[s]=a[e]; a[e]=t; s++; e--; } for(int i=0;i<n;i++) { printf("%d ",a[i]); } return 0;

}

Please read the code and try to anaylise it .

Feel free to share your thoughts and doubts in the comment section below.

See you next time.