add ipi3

ws2019/ipi/uebungen/uebung3.cpp

@@ -0,0 +1,14 @@
+#include "cpp_headers/fcpp.hh"
+
+int binomial(int n, int k) {
+    return cond(k > n,
+                0,
+                cond(k == 0 || n == k,
+                     1,
+                     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)));
+}