Recursive: Main Program

The main loop for the recursive version is almost identical to the iterative one.

The function calls are now directed to your new recursive implementations.
For successor and predecessor, you only need to pass the root and the key. The optional candidate parameter will use its default value of None for the initial call.
The logic for parsing input and printing output remains the same, showing how the implementation can be swapped without changing program flow.

# --- Main Program Logic ---
root = None
num_operations = int(input())

for _ in range(num_operations):
    line = input().strip().split()
    op, key = line[0], int(line[1])

    if op == "ins":
        root = __________(root, key)
    elif op == "find":
        result = __________(root, key)
        print(__________)
    elif op == "succ":
        result = __________(root, key)
        print(__________)
    elif op == "pred":
        result = __________(root, key)
        print(__________)

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