Create throne-inheritance.py

Author: kamyu104

Python/throne-inheritance.py

@@ -0,0 +1,53 @@
+# Time:  ctor:    O(1)
+#        birth:   O(1)
+#        death:   O(1)
+#        inherit: O(n)
+# Space: O(n)
+
+import collections
+
+
+class ThroneInheritance(object):
+
+    def __init__(self, kingName):
+        """
+        :type kingName: str
+        """
+        self.__king = kingName
+        self.__family_tree = collections.defaultdict(list)
+        self.__dead = set()
+        
+
+    def birth(self, parentName, childName):
+        """
+        :type parentName: str
+        :type childName: str
+        :rtype: None
+        """
+        self.__family_tree[parentName].append(childName)
+
+
+    def death(self, name):
+        """
+        :type name: str
+        :rtype: None
+        """
+        self.__dead.add(name)
+        
+    
+    def getInheritanceOrder(self):
+        """
+        :rtype: List[str]
+        """
+        result = []
+        stk = [self.__king]
+        while stk:  # preorder traversal
+            node = stk.pop()
+            if node not in self.__dead:
+                result.append(node)
+            if node not in self.__family_tree:
+                continue
+            for child in reversed(self.__family_tree[node]):
+                stk.append(child)
+        return result
+