import java.util.Map;
import java.util.HashMap;

public class MemoizationUsingMap { 

    static Map<Integer,Long> mzTable;

    static long mzFib(int n) {
        if (!mzTable.containsKey(n)) {
            long value = (n < 2) ? n : mzFib(n-1) + mzFib(n-2);
            mzTable.put(n, value);
        }
        return mzTable.get(n);
    }

    public static void main(String[] args) { 
        int n = Integer.parseInt(args[0]);

        if (n < 0) {
            System.err.println("argument must be a nonnegative integer");
            System.exit(1);
        }

        long value;
        double time;

        Stopwatch sw = new Stopwatch();
        mzTable = new HashMap<Integer,Long>();
        value = mzFib(n);
        time = sw.elapsedTime();
        System.out.printf("%nmzFib(%d) = %d%n", n, value);
        System.out.printf("time spent: %.2f%n", time);
    }
}