From: Skullheadx <admonty1@gmail.com>
Date: Wed, 8 Feb 2023 22:27:36 +0000 (-0500)
Subject: Update S4.py
X-Git-Url: http://git.skullheadx.com/nixos/static/projects.html?a=commitdiff_plain;h=e27b85f1a794cefe79914de8ea7b746519e86fe5;p=CCC.git

Update S4.py
---

diff --git a/Main/Python/2021/S4.py b/Main/Python/2021/S4.py
index 21c7901..98cf4be 100644
--- a/Main/Python/2021/S4.py
+++ b/Main/Python/2021/S4.py
@@ -10,48 +10,56 @@
 #
 #
 # """
+from queue import Queue
 
 
 def swap(i, j):
 	stations[i], stations[j] = stations[j], stations[i]
 
 
-def get_next_station(m, station):
-	if m > len(stations) and station != N:
-		return False
-
-	if station == N:
-		outputs.append(m)
-		return True
-	# take a walkway
-	if station in walkways:
-		for destination in walkways[station]:
-			get_next_station(m + 1, destination)
-
-	if m < len(stations):
-		train = stations[m]
-		# take a train
-		if train == station:
-			if m < len(stations) - 1:
-				get_next_station(m + 1, stations[m + 1])
-		# wait at the station
-		get_next_station(m + 1, station)
-
-
-
 N, W, D = tuple(map(int, input().split()))
 walkways = dict()
 for i in range(W):
 	A, B = tuple(map(int, input().split()))
 	walkways[A] = walkways.get(A, list()) + [B]
 
-outputs = []
-test = []
-
 stations = list(map(int, input().split()))
+
 for i in range(D):
 	X, Y = tuple(map(int, input().split()))
-	swap(X - 1, Y - 1)
-	outputs.clear()
-	get_next_station(0, 1)
-	print(min(outputs))
\ No newline at end of file
+	swap(X-1, Y-1)
+
+
+
+	q = Queue()
+	q.put((0, 1))
+
+
+
+	visited = set()
+
+	while not q.empty():
+		m, station = q.get()
+
+		if (m, station) in visited:
+			continue
+		visited.add((m, station))
+
+		if m > len(stations):
+			continue
+
+		if station == N:
+			print(m)
+			break
+		# print(f"q:{q.qsize()}")
+
+		# take a walkway
+		if station in walkways:
+			for destination in walkways[station]:
+				q.put((m + 1, destination))
+
+		# take a train
+		if stations[m] == station and m + 1 < len(stations):
+			q.put((m + 1, stations[m + 1]))
+		# wait at the station
+		q.put((m + 1, station))