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 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:
/**
* Definition for a binary tree node.
* class TreeNode {
* public $val = null;
* public $left = null;
* public $right = null;
* function __construct($val = 0, $left = null, $right = null) {
* $this->val = $val;
* $this->left = $left;
* $this->right = $right;
* }
* }
*/
class Solution {
/**
* @param TreeNode $root
* @param Integer $target
* @return TreeNode
*/
function removeLeafNodes($root, $target) {
if ($root == null) return null;
if ($root->left == null && $root->right == null && $root->val == $target)
return null;
$root->left = $this->removeLeafNodes($root->left, $target);
$root->right = $this->removeLeafNodes($root->right, $target);
if ($root->left == null && $root->right == null && $root->val == $target)
return null;
return $root;
}
}
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