[Solved] Given a binary tree root and an integer target, delete all the leaf nodes with value target.

Question

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 targetif 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:

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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:

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Input: root = [1,3,3,3,2], target = 3
Output: [1,3,null,null,2]

Example 3:

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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

Python Solution

# 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: TreeNode, target: int) -> TreeNode:
        if root:    
            root.left = self.removeLeafNodes(root.left,target)
            root.right = self.removeLeafNodes(root.right,target)
            
            if root.val==target and root.left is root.right:
                return None
        return root
Abhishek Sharma
Abhishek Sharma

Started my Data Science journey in my 2nd year of college and since then continuously into it because of the magical powers of ML and continuously doing projects in almost every domain of AI like ML, DL, CV, NLP.

Articles: 517

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