814. Binary Tree Pruning

https://leetcode.com/problems/binary-tree-pruning/

Python

Postfix Traversal

class Solution:
    def pruneTree(self, node: Optional[TreeNode]) -> Optional[TreeNode]:
        if not node:
            return

        node.left = self.pruneTree(node.left)
        node.right = self.pruneTree(node.right)
        
        if node.val == 0 and not node.left and not node.right:
            return

        return node