Description
Given a binary tree root and an integer target, delete all the leaf nodes with value target.
Note that once you delete a leaf node with value target, if its parent node becomes a leaf node and has the value target, it should also be deleted (you need to continue doing that until you cannot).
Example 1:
Input: root = [1,2,3,2,null,2,4], target = 2 Output: [1,null,3,null,4] Explanation: Leaf nodes in green with value (target = 2) are removed (Picture in left). After removing, new nodes become leaf nodes with value (target = 2) (Picture in center).
Example 2:
Input: root = [1,3,3,3,2], target = 3 Output: [1,3,null,null,2]
Example 3:
Input: root = [1,2,null,2,null,2], target = 2 Output: [1] Explanation: Leaf nodes in green with value (target = 2) are removed at each step.
Constraints:
- The number of nodes in the tree is in the range
[1, 3000]. 1 <= Node.val, target <= 1000
Solution
Python3
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def removeLeafNodes(self, root: Optional[TreeNode], target: int) -> Optional[TreeNode]:
def go(node):
if node.left:
node.left = go(node.left)
if node.right:
node.right = go(node.right)
if not node.left and not node.right and node.val == target:
return None
return node
return go(root)