1315. Sum of Nodes with Even-Valued Grandparent

Author: Partho Biswas

README.md

@@ -430,6 +430,7 @@ Check this [golden](https://tinyurl.com/ujopecz) post.
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+|39| [1315. Sum of Nodes with Even-Valued Grandparent](https://tinyurl.com/y72q6hfn) | [Python](https://tinyurl.com/wu6rdaw/1315_Sum_of_Nodes_with_Even_Valued_Grandparent.py), [Swift](https://tinyurl.com/wuja3c4/1315_Sum_of_Nodes_with_Even_Valued_Grandparent.swift) | -- | Medium | -- |
 
 </p>
 </details>

leetcode.com/python/1315_Sum_of_Nodes_with_Even_Valued_Grandparent.py

@@ -0,0 +1,49 @@
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+
+# Top-Down
+class Solution(object):
+    def sumEvenGrandparent(self, root):
+        """
+        :type root: TreeNode
+        :rtype: int
+        """
+        self.nodeSumGlobal = 0
+        self.sumEvenGrandparentHelper(root, None, None)
+        return self.nodeSumGlobal
+
+    def sumEvenGrandparentHelper(self, root, parent, grandParent):
+        if not root:
+            return 0
+        if grandParent and (grandParent.val % 2 == 0):
+            self.nodeSumGlobal += root.val
+
+        self.sumEvenGrandparentHelper(root.left, root, parent)
+        self.sumEvenGrandparentHelper(root.right, root, parent)
+
+
+# Bottom-Up
+class Solution(object):
+    def sumEvenGrandparent(self, root):
+        """
+        :type root: TreeNode
+        :rtype: int
+        """
+        nodeSum = self.sumEvenGrandparentHelper(root, None, None)
+        return nodeSum
+
+    def sumEvenGrandparentHelper(self, root, parent, grandParent):
+        if not root:
+            return 0
+
+        left = self.sumEvenGrandparentHelper(root.left, root, parent)
+        right = self.sumEvenGrandparentHelper(root.right, root, parent)
+
+        currentSum = left + right
+        if grandParent and (grandParent.val % 2 == 0):
+            currentSum += root.val
+        return currentSum