Add Open the Lock solution

practice/leetcode/solutions_00600/solution_00752.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+
+"""LeetCode solution 00752."""
+
+import unittest
+from collections import deque
+
+
+class Solution(object):
+    def openLock(self, deadends, target):
+        """
+        :type deadends: List[str]
+        :type target: str
+        :rtype: int
+        """
+        if target == "0000":
+            return 0
+
+        dead = set(deadends)
+        if "0000" in dead or target in dead:
+            return -1
+
+        queue = deque([("0000", 0)])
+        visited = {"0000"}
+
+        while queue:
+            state, steps = queue.popleft()
+
+            for neighbor in self.neighbors(state):
+                if neighbor in dead or neighbor in visited:
+                    continue
+
+                if neighbor == target:
+                    return steps + 1
+
+                visited.add(neighbor)
+                queue.append((neighbor, steps + 1))
+
+        return -1
+
+    def neighbors(self, state):
+        for i in range(4):
+            digit = int(state[i])
+
+            for move in (-1, 1):
+                new_digit = (digit + move) % 10
+                yield state[:i] + str(new_digit) + state[i + 1:]
+
+
+class TestSolution(unittest.TestCase):
+    def test_openLock(self):
+        solution = Solution()
+
+        self.assertEqual(
+            solution.openLock(["0201", "0101", "0102", "1212", "2002"], "0202"),
+            6,
+        )
+        self.assertEqual(solution.openLock(["8888"], "0009"), 1)
+        self.assertEqual(
+            solution.openLock(["8887", "8889", "8878", "8898", "8788", "8988", "7888", "9888"], "8888"),
+            -1,
+        )
+        self.assertEqual(solution.openLock(["0000"], "8888"), -1)
+        self.assertEqual(solution.openLock([], "0000"), 0)
+
+
+if __name__ == '__main__':
+    unittest.main()