Create path-crossing.py

Author: kamyu104

Python/path-crossing.py

@@ -0,0 +1,24 @@
+# Time:  O(n)
+# Space: O(n)
+
+class Solution(object):
+    def isPathCrossing(self, path):
+        """
+        :type path: str
+        :rtype: bool
+        """
+        x = y = 0
+        lookup = {(0, 0)}
+        for c in path:
+            if c == 'E':
+                x += 1
+            elif c == 'W':
+                x -= 1
+            elif c == 'N':
+                y += 1
+            elif c == 'S':
+                y -= 1
+            if (x, y) in lookup:
+                return True
+            lookup.add((x, y))
+        return False