add ipi3

ws2019/ipi/uebungen/binomial.cpp

@@ -0,0 +1,18 @@
+#include "cpp_headers/fcpp.hh"
+
+// Berechnet den Binomialkoeffizienten (n ueber k) rekursiv
+int binomial(int n, int k) {
+    return cond(k > n,
+                // Falls k > n: n ueber k = 0
+                0,
+                cond(k == 0 || n == k,
+                     // Falls k = 0 oder n = k: n ueber k = 1
+                     1,
+                     // sonst rekursiv berechnen
+                     binomial(n-1, k-1) + binomial(n-1, k)));
+}
+
+int main(int argc, char **argv) {
+    return print(binomial(readarg_int(argc, argv, 1),
+                          readarg_int(argc, argv, 2)));
+}