1 files changed, 43 insertions, 0 deletions
diff --git a/c/wip/053-combinatoric-selections.c b/c/wip/053-combinatoric-selections.c
new file mode 100644
index 0000000..9006f5a
--- /dev/null
+++ b/c/wip/053-combinatoric-selections.c
@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+
+typedef long long unsigned int Natural;
+
+Natural factorial(Natural n)
+{
+    if (n == 1 || n == 0) return 1;
+    else return n * factorial(n - 1);
+}
+
+Natural combination(Natural n, Natural r)
+{
+    if (r > n) exit(1);
+    Natural num = 0;
+    /* for (Natural i = 0; i < r - 1; i++) */
+    /*     num *= n - i; */
+    /* return num / factorial(r); */
+    /* if (factorial(r) * factorial(n - r) == 0) return 0; */
+    return (factorial(n) / (factorial(r) * factorial(n - r)));
+    /* return  (factorial(r) * factorial(n - r)); */
+}
+
+int main(void)
+{
+    printf("10! = %llu\n", factorial(10));
+    printf("23! = %llu\n", factorial(23));
+    printf("(23 - 10)! = %llu\n", factorial(23 - 10));
+    int counter = 0;
+    Natural comb = 0, n, r;
+    /* for (n = 1; n <= 24; n++) */
+    /*     for (r = 1; r <= n; r++) { */
+    /*         comb = combination(n, r); */
+    /*         if (comb > 1000000) { */
+    /*             counter++; */
+    /* comb = combination(23, 10); */
+                printf("%llu C %llu = %llu\n", n, r, comb);
+            /* } */
+        /* } */
+    printf("counter = %d", counter);
+    return 0;
+}