Implement main logic for counting crossings and determining final position in the lock mechanism

Day1/Part2/input.txt

@@ -4033,4 +4033,4 @@ R17
 L19
 R42
 R48
-R39
+R39

Day1/Part2/main.py

@@ -0,0 +1,32 @@
+def count_crossings_segment(P, delta):
+    P_new = P + delta
+    if delta > 0:
+        # positive Drehung: 100 * m in (P, P_new]
+        crossings = (P_new // 100) - (P // 100)
+    elif delta < 0:
+        # negative Drehung: 100 * m in [P_new, P-1]
+        crossings = ((P - 1) // 100) - ((P_new - 1) // 100)
+    else:
+        crossings = 0
+    return crossings, P_new
+
+passes = 0
+P = 50  # „entfaltete“ Position, nicht mod 100!
+
+with open("input.txt", encoding="utf-8") as f:
+    for line in f:
+        line = line.strip()
+        if not line:
+            continue
+
+        d = line[0].upper()
+        steps = int(line[1:])
+
+        delta = steps if d == 'R' else -steps
+        c, P = count_crossings_segment(P, delta)
+        passes += c
+
+final_pos = P % 100
+
+print("Anzahl 0-PASSAGEN:", passes)
+print("Endposition auf dem Schloss:", final_pos)