Delete Leaves With a Given Value

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Problem is here https://leetcode.com/problems/delete-leaves-with-a-given-value/

1325. Delete Leaves With a Given Value
Medium
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 it's parent node becomes a leaf node and has the value target, it should also be deleted (you need to continue doing that until you can't).

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.
Example 4:
Input: root = [1,1,1], target = 1
Output: []
Example 5:
Input: root = [1,2,3], target = 1
Output: [1,2,3]

Constraints:
  • 1 <= target <= 1000
  • Each tree has at most 3000 nodes.
  • Each node's value is between [1, 1000].
A very similar problem was covered in this blog before:
https://dreaktor.com/2017/09/deleting-leaves-of-certain-kind.html

Classic Post-Order traversal, code is very simple and concise - cheers, ACC.


public class Solution
{
    public TreeNode RemoveLeafNodes(TreeNode root, int target)
    {
        if (root == null) return null;
        root.left = RemoveLeafNodes(root.left, target);
        root.right = RemoveLeafNodes(root.right, target);
        if (root.left == null && root.right == null && root.val == target) return null;
        return root;
    }
}

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