Learn to think like a stronger engineer.

// Don't memorize the solution.
// Learn why the pattern works.

public int[] replaceElements(int[] arr) {

    int maxRight = -1;

    for (
        int i = arr.length - 1;
        i >= 0;
        i--
    ) {

        int current = arr[i];

        arr[i] = maxRight;

        maxRight =
            Math.max(maxRight, current);
    }

    return arr;
}

✓ Pattern: Running suffix maximum
✓ Time: O(n)
✓ Extra Space: O(1)
✓ Next: Prefix / Suffix patterns