day 6HEADmaster

1 files changed, 51 insertions, 0 deletions

diff --git a/06.c b/06.c
new file mode 100644
index 0000000..d4bb7f5
--- /dev/null
+++ b/06.c
@@ -0,0 +1,51 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+#include <err.h>
+#include "input.h"
+
+#define INPUT "input/06.txt"
+#define EXPECTED1 1598L
+#define EXPECTED2 2414L
+
+void find_marker(char* input, size_t marker_size, size_t expected) {
+	size_t pos;
+	size_t pos_max = strlen(input);
+	if(marker_size >= pos_max) {
+		err(2, "input is too short");
+		return;
+	}
+	size_t marker_size_loop = marker_size - 1;
+	for(pos = marker_size_loop; pos < pos_max; pos++) {
+		bool is_marker = true;
+		for(size_t i = pos; i > pos-marker_size_loop; i--) {
+			for(size_t j = i-1; j >= pos-marker_size_loop; j--) {
+				is_marker &= input[i] != input[j];
+				if(!is_marker)
+					break;
+			}
+			if(!is_marker)
+				break;
+		}
+		if(is_marker)
+			break;
+	}
+	
+	pos++;
+	CHECK(pos, expected)
+}
+
+int main() {
+	// read input
+	struct input_str input;
+	input_str_read(&input, INPUT);
+
+	// do stuff
+	find_marker(input.lines[0], 4, EXPECTED1);
+	find_marker(input.lines[0], 14, EXPECTED2);
+
+	// cleanup & exit
+	input_str_free(&input);
+	return 0;
+}