\begin{lstlisting}[caption={Rekursive Implementierung der Fibonacci-Zahlen in C}]
#define MAX_N 100
#define UNSET -1

long memo[MAX_N];
memset(memo, UNSET, MAX_N * sizeof(long));
memo[1] = 1; memo[2] = 1;

long fib(int n) {
	if (memo[n] != UNSET) return memo[n];
	memo[n] = fib(n-1) + fib(n-2);
	return memo[n];
}
\end{lstlisting}