Initial data commit

Task/Damm-algorithm/C/damm-algorithm.c

@@ -0,0 +1,30 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+
+bool damm(unsigned char *input, size_t length) {
+    static const unsigned char table[10][10] = {
+        {0, 3, 1, 7, 5, 9, 8, 6, 4, 2},
+        {7, 0, 9, 2, 1, 5, 4, 8, 6, 3},
+        {4, 2, 0, 6, 8, 7, 1, 3, 5, 9},
+        {1, 7, 5, 0, 9, 8, 3, 4, 2, 6},
+        {6, 1, 2, 3, 0, 4, 5, 9, 7, 8},
+        {3, 6, 7, 4, 2, 0, 9, 5, 8, 1},
+        {5, 8, 6, 9, 7, 2, 0, 1, 3, 4},
+        {8, 9, 4, 5, 3, 6, 2, 0, 1, 7},
+        {9, 4, 3, 8, 6, 1, 7, 2, 0, 5},
+        {2, 5, 8, 1, 4, 3, 6, 7, 9, 0},
+    };
+
+    unsigned char interim = 0;
+    for (size_t i = 0; i < length; i++) {
+        interim = table[interim][input[i]];
+    }
+    return interim == 0;
+}
+
+int main() {
+    unsigned char input[4] = {5, 7, 2, 4};
+    puts(damm(input, 4) ? "Checksum correct" : "Checksum incorrect");
+    return 0;
+}