c 2024 day 5 part 1

c/2024/5/print_queue.c

@@ -0,0 +1,83 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+#include "../../lib/aoc.h"
+
+typedef struct Rule {
+  int first;
+  int last;
+} Rule;
+
+typedef struct Rules {
+  Rule rule[1200];
+  int length;
+} Rules;
+
+typedef struct Update {
+  int page[100];
+  int length;
+} Update;
+
+bool valid_rule(Rule *rule, Update *update) {
+  int first = -1, last = -1;
+  for (int i = 0; i < update->length; i++) {
+    if (rule->first == update->page[i]) first = i;
+    if (rule->last == update->page[i]) last = i;
+    if (first != -1 && last != -1) return first < last;
+  }
+
+  return true;
+}
+
+bool valid_update(Rules *rules, Update *update) {
+  for (int i = 0; i < rules->length; i++) {
+    if (!valid_rule(&(rules->rule[i]), update)) return false;
+  }
+  return true;
+}
+
+int middle_page_number(Update *update) {
+  return update->page[update->length / 2];
+}
+
+int main() {
+  char *line;
+
+  int sum = 0;
+
+  Rules rules;
+  int rule_index = 0;
+  int first, last;
+
+  Update update;
+  char *update_element;
+
+  bool scanning_rules = true;
+  while ((line = aoc_read_line()) != NULL) {
+    if (scanning_rules) {
+      if (strlen(line) == 0) scanning_rules = false;
+      else {
+	sscanf(line, "%d|%d", &first, &last);
+	rules.rule[rules.length].first = first;
+	rules.rule[rules.length].last = last;
+	rules.length++;
+      }
+    } else {
+      update.length = 0;
+      update_element = strtok(line, ",");
+      while(update_element != NULL) {
+	update.page[update.length++] = atoi(update_element);
+	update_element = strtok(NULL, ",");
+      }
+      if (valid_update(&rules, &update)) sum += middle_page_number(&update);
+    }
+  }
+
+  printf("Part 1: %d\n", sum);
+  // printf("Part 2: %d\n", xmas_sum);
+
+  aoc_free();
+  return 0;
+}