Reverse an Array

Easy
0/40
Average time to solve is 10m
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SamsungHealspan

Problem statement

Given an array 'arr' of size 'n'.


Return an array with all the elements placed in reverse order.


Note: 
You don’t need to print anything. Just implement the given function.
Example: 
Input: n = 6, arr = [5, 7, 8, 1, 6, 3]

Output: [3, 6, 1, 8, 7, 5]

Explanation: After reversing the array, it looks like this [3, 6, 1, 8, 7, 5].
Detailed explanation ( Input/output format, Notes, Images )
Input Format: 
The first line contains an integer n, the size of the array
The second line contains n integers, the array.
Output format: 
Return the reversed array.
Sample Input 1:
8
3 1 1 7 4 2 6 11
Sample Output 1:
11 6 2 4 7 1 1 3
Explanation Of Sample Input 1 :
After reversing the array, it looks like this [11, 6, 2, 4, 7, 1, 1, 3].
Sample Input 2:
4
8 1 3 2
Sample Output 2:
2 3 1 8
Explanation Of Sample Input 2 :
After reversing the array, it looks like this [2, 3, 1, 8].
Expected time complexity
The expected time complexity is O(n).
Constraints:
1 <= 'n' <= 10^6
-10^9 <= 'arr[i]' <=10^9
Hint

Use an extra array.

Approaches (4)
Using an extra array

Approach:

  • Create a new array, say,  ‘arr1’.
  • Iterate from index ‘0’ to ‘n-1’ and arr1[i]  = arr[n-1-i]

Algorithm:

  • Create a new array arr1 of size n
  • For ‘i’ from 0 to n-1
    • arr1[i] =arr[n-1-i];
  • Return arr1;


 

Time Complexity

O(n), Where n is the size of the array

 

We are iterating through the array once. 

 

Hence the time complexity would be O(n).

Space Complexity

O(n) where n is the size of the array

 

Since we are creating a new array of size n. 

 

Hence the space complexity would be O(n).

Code Solution
(100% EXP penalty)
Reverse an Array
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