day6 part 2

day6/README.md

@@ -42,3 +42,21 @@ Here are a few more examples:
 - `zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw`: first marker after character **11**
 
 How many characters need to be processed before the first start-of-packet marker is detected?
+
+## Part Two
+
+Your device's communication system is correctly detecting packets, but still isn't working. It looks like it also needs
+to look for **messages**.
+
+A **start-of-message marker** is just like a start-of-packet marker, except it consists of **14 distinct characters** rather
+than 4.
+
+Here are the first positions of start-of-message markers for all of the above examples:
+
+- `mjqjpqmgbljsphdztnvjfqwrcgsmlb`: first marker after character **19**
+- `bvwbjplbgvbhsrlpgdmjqwftvncz`: first marker after character **23**
+- `nppdvjthqldpwncqszvftbrmjlhg`: first marker after character **23**
+- `nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg`: first marker after character **29**
+- `zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw`: first marker after character **26**
+
+**How many characters need to be processed before the first start-of-message marker is detected?**

day6/main.py

@@ -1,24 +1,28 @@
 from common.file import read_data
 
 test_cases = [
-    {"input": "mjqjpqmgbljsphdztnvjfqwrcgsmlb", "expect": 7},
-    {"input": "bvwbjplbgvbhsrlpgdmjqwftvncz", "expect": 5},
-    {"input": "nppdvjthqldpwncqszvftbrmjlhg", "expect": 6},
-    {"input": "nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg", "expect": 10},
-    {"input": "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw", "expect": 11},
+    {"input": "mjqjpqmgbljsphdztnvjfqwrcgsmlb", "packet": 7, "message": 19},
+    {"input": "bvwbjplbgvbhsrlpgdmjqwftvncz", "packet": 5, "message": 23},
+    {"input": "nppdvjthqldpwncqszvftbrmjlhg", "packet": 6, "message": 23},
+    {"input": "nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg", "packet": 10, "message": 29},
+    {"input": "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw", "packet": 11, "message": 26},
 ]
 
 
-def end_of_start_marker_1(data: str) -> int:
-    # use 2 counters
+def end_of_start_marker(data: str) -> int:
+    return _process_signal(data, 4)
+
+
+def end_of_message(data: str) -> int:
+    return _process_signal(data, 14)
+
+
+def _process_signal(signal: str, size: int) -> int:
     i = 0
-    j = 4
-    while j < len(data):
-        # read data by window of 4 characters
-        packet = data[i:j]
-        # check if all are different
+    j = size
+    while j < len(signal):
+        packet = signal[i:j]
         if len(set(packet)) == len(packet):
-            # if yes return end counter
             return j
 
         i += 1
@@ -29,8 +33,13 @@ def end_of_start_marker_1(data: str) -> int:
 
 if __name__ == "__main__":
     for test in test_cases:
-        res = end_of_start_marker_1(test["input"])
-        assert res == test["expect"], f"{res} is not the right value, want {test['expect']}"
+        res = end_of_start_marker(test["input"])
+        assert res == test["packet"], f"{res} is not the right value, want {test['packet']}"
+
+    for test in test_cases:
+        res = end_of_message(test["input"])
+        assert res == test["message"], f"{res} is not the right value, want {test['message']}"
 
     dataset = read_data()
-    print(end_of_start_marker_1(dataset[0]))
+    print(end_of_start_marker(dataset[0]))
+    print(end_of_message(dataset[0]))