BFS

lc752. Open the Lock.py

@@ -0,0 +1,42 @@
+class Solution:
+    def openLock(self, deadends, target):
+        """
+        :type deadends: List[str]
+        :type target: str
+        :rtype: int
+        """
+        deadset = set(deadends)
+        if '0000' in deadset:
+            return -1
+        import queue
+        setps = 0
+        q = queue.Queue()
+        q.put('0000')
+        visited = {'0000'}
+
+        while not q.empty():
+            setps += 1
+            length = q.qsize()
+            for _ in range(length):
+
+                node = q.get()
+
+                for i in range(4):
+                    for j in (-1, 1):
+                        slst = list(node)
+                        slst[i] = str((int(slst[i]) + j) % 10)
+                        tem = ''.join(slst)
+                        if tem == target:
+                            return setps
+                        if tem not in visited and tem not in deadset:
+                            q.put(tem)
+                        visited.add(tem)
+
+        return -1
+
+
+deadends = ["0000"]
+target = "8888"
+s = Solution()
+
+print(s.openLock(deadends, target))