1325. Delete Leaves With a Given Value

Posted on Edited on In

1325. Delete Leaves With a Given Value

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:

1
2
3
4
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:

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

Example 3:

1
2
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

Hints/Notes

  • binary tree

Solution

Language: C++

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left),
 * right(right) {}
 * };
 */
class Solution {
public:
    TreeNode* removeLeafNodes(TreeNode* root, int target) {
        if (!root) {
            return root;
        }

        root->left = removeLeafNodes(root->left, target);
        root->right = removeLeafNodes(root->right, target);

        if (root->val == target && !root->left && !root->right) {
            return nullptr;
        }
        return root;
    }
};