day6 c

1 files changed, 54 insertions, 0 deletions

diff --git a/2022/day6/day6.c b/2022/day6/day6.c
new file mode 100644
index 0000000..13d5c04
--- /dev/null
+++ b/2022/day6/day6.c
@@ -0,0 +1,54 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include "../util.h"
+
+// char filename[] = "ref.txt";
+char filename[] = "pzl.txt";
+
+#define BUF_LEN 10000
+u8 buf[BUF_LEN];
+#define NAH_LEN 26
+u8 not_a_hashmap[NAH_LEN];
+
+s32 solve(u32 n)
+{
+	int fd = open(filename, O_RDONLY);
+	u32 data_len = read(fd, buf, LEN(buf));
+	if (data_len == LEN(buf)) {
+		printf("buffer probably not big enough\n");
+		exit(1);
+	}
+
+	for (u32 i = n; i < data_len; ++i) {
+		memset(not_a_hashmap, 0x00, LEN(not_a_hashmap));
+
+		for (u32 j = 1; j <= n; ++j) {
+			u32 index = (buf[i-j]-'a');
+			if (index >= NAH_LEN) {
+				printf("nah too small\n");
+				exit(1);
+			}
+			not_a_hashmap[index] = 1;
+		}
+
+		u32 sum = 0;
+		for (u32 j = 0; j < NAH_LEN; ++j) {
+			sum += not_a_hashmap[j];
+		}
+		if (sum == n) {
+			return i;
+		}
+
+	}
+	return -1;
+}
+
+int main()
+{
+	printf("res1: %d\n", solve(4));
+	printf("res2: %d\n", solve(14));
+}
+