From a56f3b726637e2140ab8d7ca2981649167f1ea70 Mon Sep 17 00:00:00 2001
From: June McEnroe <june@causal.agency>
Date: Tue, 15 Dec 2020 00:06:58 -0500
Subject: Solve day 15 part 1

---
 2020/day15.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 2020/day15.c

(limited to '2020/day15.c')

diff --git a/2020/day15.c b/2020/day15.c
new file mode 100644
index 0000000..f5ee806
--- /dev/null
+++ b/2020/day15.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+#include <stdlib.h>
+int main(void) {
+	int nums[2048];
+	int len = 0;
+	while (0 < scanf("%d,", &nums[len])) {
+		len++;
+	}
+	while (len < 2020) {
+		int last = nums[len-1];
+		int next = 0;
+		for (int i = len - 2; i >= 0; --i) {
+			if (nums[i] == last) {
+				next = len - 1 - i;
+				break;
+			}
+		}
+		nums[len++] = next;
+	}
+	printf("%d\n", nums[len-1]);
+}
-- 
cgit 1.4.1