c 2024 day 5 part 2

c/2024/5/print_queue.c

@@ -42,10 +42,29 @@ int middle_page_number(Update *update) {
   return update->page[update->length / 2];
 }
 
+void reorder_update(Rules *rules, Update *update) {
+  bool dirty = true;
+  while (dirty) {
+    dirty = false;
+    for (int i = 0; i < update->length - 1; i++) {
+      for (int j = 0; j < rules->length; j++) {
+	Rule rule = rules->rule[j];
+	if (update->page[i] == rule.last && update->page[i + 1] == rule.first) {
+	  dirty = true;
+	  update->page[i] = rule.first;
+	  update->page[i + 1] = rule.last;
+	  break;
+	}
+      }
+    }
+  }
+}
+
 int main() {
   char *line;
 
   int sum = 0;
+  int reorder_sum = 0;
 
   Rules rules;
   int rule_index = 0;
@@ -72,11 +91,15 @@ int main() {
 	update_element = strtok(NULL, ",");
       }
       if (valid_update(&rules, &update)) sum += middle_page_number(&update);
+      else {
+	reorder_update(&rules, &update);
+	reorder_sum += middle_page_number(&update);
+      }
     }
   }
 
   printf("Part 1: %d\n", sum);
-  // printf("Part 2: %d\n", xmas_sum);
+  printf("Part 2: %d\n", reorder_sum);
 
   aoc_free();
   return 0;