C 2024 day 1

c/2024/1/historian_hysteria.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "../../lib/aoc.h"
+
+int sort(const void *a, const void *b) {
+  return *(int*) a - *(int*) b;
+}
+
+int main() {
+  char *line;
+
+  int left[1000];
+  int right[1000];
+  int index = 0;
+
+  while ((line = aoc_read_line()) != NULL) {
+    int l, r;
+    sscanf(line, "%d %d", &l, &r);
+    left[index] = l;
+    right[index] = r;
+    index++;
+  }
+
+  qsort(left, 1000, sizeof(int), sort);
+  qsort(right, 1000, sizeof(int), sort);
+
+  int sum = 0;
+
+  for (int i = 0; i < 1000; i++) {
+    sum += abs(left[i] - right[i]);
+  }
+
+  printf("Part 1: %d\n", sum);
+
+  int similarity_score = 0;
+  for (int i = 0; i < 1000; i++) {
+    int right_count = 0;
+    for (int j = 0; j < 1000; j++) {
+      if (left[i] == right[j]) right_count++;
+    }
+    similarity_score += (left[i] * right_count);
+  }
+
+  printf("Part 2: %d\n", similarity_score);
+
+  aoc_free();
+  return 0;
+}