LeetCode : 1302 Deepest Leaves Sum | Depth First Search (DFS) Solution with Python

 

LeetCode Problem : https://leetcode.com/problems/deepest-leaves-sum/description/

# 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
class Solution(object):
    height = 0 
    result = 0 
    def deepestLeavesSum(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        self.helper(root,1)
        return self.result

    def helper(self, root , depth ) :
        if root is None :
            return 0 

        # Check if it is a Leaf Node and Depth is greater than Heigh 
        # Then update result variable
        if depth > self.height and root.left is None and root.right is None  :
            self.height = depth
            self.result =  root.val
        elif depth == self.height: 
            # If nodes are at same depth then , add value to global result.
            self.result += root.val    

        # During each node traversal , increase depth by 1.   
        left = self.helper(root.left,depth +1 )
        right = self.helper(root.right ,depth +1 )