Create all-paths-from-source-lead-to-destination.py

Author: kamyu104

Python/all-paths-from-source-lead-to-destination.py

@@ -0,0 +1,35 @@
+# Time:  O(n + e)
+# Space: O(n + e)
+
+import collections
+
+
+class Solution(object):
+    def leadsToDestination(self, n, edges, source, destination):
+        """
+        :type n: int
+        :type edges: List[List[int]]
+        :type source: int
+        :type destination: int
+        :rtype: bool
+        """
+        UNVISITED, VISITING, DONE = range(3)
+        def dfs(children, node, destination, status):
+            if status[node] == DONE:
+                return True
+            if status[node] == VISITING:
+                return False
+            status[node] = VISITING
+            if node not in children and node != destination:
+                return False
+            if node in children:
+                for child in children[node]:
+                    if not dfs(children, child, destination, status):
+                        return False
+            status[node] = DONE
+            return True
+        
+        children = collections.defaultdict(list)
+        for parent, child in edges:
+            children[parent].append(child)
+        return dfs(children, source, destination, [0]*n)