1 files changed, 56 insertions, 0 deletions
diff --git a/Advent-of-Code-2022/aoc-6/main.c b/Advent-of-Code-2022/aoc-6/main.c
new file mode 100644
index 0000000..d9cf652
--- /dev/null
+++ b/Advent-of-Code-2022/aoc-6/main.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if 0
+  #define PART(line) part(line, 4)
+#else
+  #define PART(line) part(line, 14)
+#endif
+
+#if 0
+  #define FILENAME "sample.txt"
+#else
+  #define FILENAME "input.txt"
+#endif
+
+void part(char *line, int n)
+{
+    n--;
+    int times_seen['z'-'a'+1] = {0};
+
+    for(ulong i = n; i < strlen(line) - 1; i++)
+    {
+        int stop = 0;
+        for(ulong j = i-n; j <= i && !stop; j++)
+            if(++(times_seen[line[j]-'a']) > 1)
+                stop = 1;
+
+        memset(times_seen, 0, sizeof(times_seen));
+        if(stop) continue;
+
+        printf("%ld\n", i + 1);
+        return;
+    }
+}
+
+void parse()
+{
+    FILE *fp = fopen(FILENAME, "r");
+    if(!fp) {
+        fprintf(stderr, "ERROR: Could not open file: %s\n", FILENAME);
+        exit(1);
+    }
+
+    char line[4096];
+    while(fgets(line, sizeof(line), fp))
+        PART(line);
+
+    fclose(fp);
+}
+
+int main(void)
+{
+    parse();
+    return 0;
+}