From 949dfdcea0a2df5d5e01dc7453d6e56afce40324 Mon Sep 17 00:00:00 2001
From: Bill Rossi <bassguitarbill@gmail.com>
Date: Thu, 18 Jul 2024 21:06:39 -0400
Subject: [PATCH] C 2017 day 1

---
 bin/run            |  2 +-
 c/2017/1/problem.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 c/2017/1/problem.c

diff --git a/bin/run b/bin/run
index 02de37a..4c45a47 100755
--- a/bin/run
+++ b/bin/run
@@ -16,7 +16,7 @@ fi
 
 year=$(($2))
 
-if [[ $year -gt 2015 ]]
+if [[ $year -lt 2015 ]]
 then
     echo "invalid year: $2"
     echo "must be 2015 or later"
diff --git a/c/2017/1/problem.c b/c/2017/1/problem.c
new file mode 100644
index 0000000..2b60143
--- /dev/null
+++ b/c/2017/1/problem.c
@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+  FILE* input = fopen("../data/2017/1/input.txt", "r");
+  char c1, c2, first_char;
+  long total;
+
+  fread(&first_char, 1, 1, input);
+  c2 = first_char;
+
+  while (fread(&c1, 1, 1, input) > 0 && c1 != '\n') {
+    if (c1 == c2) {
+      total += c1 - '0';
+    }
+    c2 = c1;
+  }
+
+  if (c2 == first_char) {
+    total += c2 - '0';
+  }
+
+  printf("Part 1: %d\n", total);
+
+  int num_chars = ftell(input);
+  rewind(input);
+  total = 0;
+
+  char *buffer = malloc(num_chars);
+  fread(buffer, 1, num_chars, input);
+
+  for(int i = 0; i < num_chars / 2; i++) {
+    c1 = buffer[i];
+    c2 = buffer[i + (num_chars / 2)];
+    if (c1 == c2) {
+      total += c1 - '0';
+    }
+  }
+
+  total <<= 1;
+
+  printf("Part 2: %d\n", total);
+}