✍️ First Attempt: Reversing Using a Temporary Array

This is the approach many beginners (myself included) think of first:
“Why not create a new array and fill it in reverse order?”

#include <iostream>
#include <vector>
using namespace std;

void reverseArray(vector<int> &arr) {
    int n = arr.size();
    vector<int> temp(n);

    for (int i = 0; i < n; i++)
        temp[i] = arr[n - i - 1];

    for (int i = 0; i < n; i++)
        arr[i] = temp[i];
}

int main() {
    vector<int> arr = {1, 4, 3, 2, 6, 5};
    reverseArray(arr);

    for (int val : arr)
        cout << val << " ";
}

🔍 Analysis
✅ Simple and readable
❌ Not memory-efficient – It uses an extra array of the same size (O(n) space)

✅ Optimal Approach: In-Place Reversal Using Swapping

Then I explored another way—swapping elements from both ends of the array until the middle is reached.

void reverseArray(vector<int>& arr) {
    int left = 0, right = arr.size() - 1;
    while (left < right) {
        swap(arr[left], arr[right]);
        left++;
        right--;
    }
}

Or Using a For Loop:

void reverseArray(vector<int>& arr) {
    for (int i = 0; i < arr.size() / 2; i++) {
        swap(arr[i], arr[arr.size() - 1 - i]);
    }
}

🔍 Analysis
✅ Efficient – Reverses the array in O(n) time and O(1) space
✅ Professional standard – Used in interviews and real-world problems
✅ Doesn't require extra memory