Data commit

Task/Lah-numbers/C/lah-numbers.c

@@ -0,0 +1,38 @@
+#include <stdint.h>
+#include <stdio.h>
+
+uint64_t factorial(uint64_t n) {
+    uint64_t res = 1;
+    if (n == 0) return res;
+    while (n > 0) res *= n--;
+    return res;
+}
+
+uint64_t lah(uint64_t n, uint64_t k) {
+    if (k == 1) return factorial(n);
+    if (k == n) return 1;
+    if (k > n) return 0;
+    if (k < 1 || n < 1) return 0;
+    return (factorial(n) * factorial(n - 1)) / (factorial(k) * factorial(k - 1)) / factorial(n - k);
+}
+
+int main() {
+    int row, i;
+
+    printf("Unsigned Lah numbers: L(n, k):\n");
+    printf("n/k ");
+    for (i = 0; i < 13; i++) {
+        printf("%10d ", i);
+    }
+    printf("\n");
+    for (row = 0; row < 13; row++) {
+        printf("%-3d", row);
+        for (i = 0; i < row + 1; i++) {
+            uint64_t l = lah(row, i);
+            printf("%11lld", l);
+        }
+        printf("\n");
+    }
+
+    return 0;
+}