Today's Challenge

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

Binary Tree Pruning - LeetCode

오랫만에 돌아온 트리 순회 문제

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

            lco = co(node.left)
            rco = co(node.right)

            if not lco:
                node.left = None
            if not rco:
                node.right = None

            return node.val or lco or rco
    
        return root if co(root) else None