#!/usr/bin/env python3
"""Memoized Fibonacci calculator - returns the n-th fibonacci number."""

from functools import lru_cache

@lru_cache(maxsize=None)
def fib(n: int) -> int:
    """Return the n-th fibonacci number (0-indexed: fib(0)=0, fib(1)=1)."""
    if n < 0:
        raise ValueError("n must be non-negative")
    if n <= 1:
        return n
    return fib(n - 1) + fib(n - 2)

def main():
    results = [(n, fib(n)) for n in range(15)]
    print("n | fib(n)")
    print("--+------")
    for n, val in results:
        print(f"{n} | {val}")
    
    # Verify known values
    assert fib(0) == 0, "fib(0) should be 0"
    assert fib(1) == 1, "fib(1) should be 1"
    assert fib(10) == 55, "fib(10) should be 55"
    assert fib(14) == 377, "fib(14) should be 377"
    print("\nAll assertions passed!")

if __name__ == "__main__":
    main()