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1325. Delete Leaves With a Given Value

Difficulty Topics

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

delete-leaves-with-a-given-value.py
# 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 dfs(self, root, target):
        if not root: return None

        root.left = self.dfs(root.left, target)
        root.right = self.dfs(root.right, target)

        if root.left == root.right == None and root.val == target: return None

        return root




    def removeLeafNodes(self, root: TreeNode, target: int) -> TreeNode:
        return self.dfs(root, target)