1302. Deepest Leaves Sum

Medium | Tree + Level-order Traversal | 80 ms (98.31%), 17.7 MB (89.56%)

❓ Problem Statement

Source: LeetCode - Deepest Leaves Sum GitHub: Solution / Performance

Given the root of a binary tree, return the sum of values of its deepest leaves.

✍🏻 Constraints & Example

💡 Ideas

Extension question of Level-order traversal.

Follow the level-order traversal, keep maintaining the sum of all nodes' values in the current level until the final iteration.

🤖 Python3

class Solution:
    def deepestLeavesSum(self, root: TreeNode) -> int:
        # (base case)
        if not root.left and not root.right: return root.val
        
        # ==================================================
        #  Binary Tree + Level Order Traversal             =
        # ==================================================
        # time  : O(n)
        # space : O(n)
        
        ans = 0
        stack = [root]
        
        while stack:
            ans = 0
            
            # loop through stack for current length, pop the first node
            for i in range(len(stack)):
                node = stack.pop(0)
                ans += node.val
                
                if node.left: stack.append(node.left)
                if node.right: stack.append(node.right)
                    
        return ans

🤖 Java