LC 1306

Author: jsgoller1

leetcode/1306-jump-game-iii/solution.py

@@ -0,0 +1,31 @@
+from typing import List
+
+
+class Solution:
+    def canReach(self, arr: List[int], start: int) -> bool:
+        visited = set()
+
+        def dfs(idx):
+            if idx in visited:
+                return False
+            if arr[idx] == 0:
+                return True
+            visited.add(idx)
+            jump = arr[idx]
+            hi, lo = idx+jump, idx-jump
+            res = dfs(hi) if hi < len(arr) else False
+            res |= dfs(lo) if 0 <= lo else False
+            return res
+
+        return dfs(start)
+
+
+s = Solution()
+cases = [
+    ([4, 2, 3, 0, 3, 1, 2], 5, True),
+    ([4, 2, 3, 0, 3, 1, 2], 0, True),
+    ([3, 0, 2, 1, 2], 2, False),
+]
+for arr, start, expected in cases:
+    actual = s.canReach(arr, start)
+    assert actual == expected, f"{arr, start}: {expected} != {actual}"