Reverse an array in place

Challenge

Reverse an array in place using two indices that meet in the middle.

Task

Implement void reverse_array(int *a, int n) that reverses the order of the first n elements of a, modifying the array in place (no extra array). Use two indices, one from each end, swapping and moving inward. No main — the grader calls it.

Input

A pointer a to at least n ints, and the count int n (n >= 0).

Output

No return value. After the call, the first n elements are in reversed order.

Example

{1,2,3,4}   ->   {4,3,2,1}
{1,2,3}     ->   {3,2,1}
{9}         ->   {9}

Edge cases

• A single-element (or empty) array is unchanged.

Rules

• Reverse in place — do not allocate a second array.

Input format

A pointer a to n ints, and the count int n (n >= 0).

Output format

No return value; the first n elements are reversed in place.

Constraints

Reverse in place; no auxiliary array.

Starter code

void reverse_array(int *a, int n) {
    /* TODO */
}