REVERSE ARRAY

Reverse Array (Using Temporary Array)
Code:

def reverseArray(arr):
    n = len(arr)
    temp = [0] * n
    for i in range(n):
        temp[i] = arr[n - i - 1]
    for i in range(n):
        arr[i] = temp[i]

Idea

2. Create a temporary array
3. Store elements in reverse order
4. Copy back to original array

Key Logic

temp[i] = arr[n - i - 1]
n - i - 1 gives reverse index

Example
[1, 4, 3] → [3, 4, 1]

Important Points

1. Time Complexity → O(n)
2. Space Complexity → O(n) (extra array used)
3. Easy to understand (beginner-friendly)
4. Not optimal (uses extra memory)

Best Alternative

1. Use two-pointer method → O(1) space
2. Use arr.reverse() → simplest

Works in two steps:

1. Copy reversed elements into temp
2. Copy back to original array