Delete Leaves With a Given Value — C++

// Time:  O(n)
// Space: O(h)

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */

class Solution {
public:
    TreeNode* removeLeafNodes(TreeNode* root, int target) {
        if (!root) {
            return nullptr;
        }
        root->left = removeLeafNodes(root->left, target);
        root->right = removeLeafNodes(root->right, target);
        return (root->left == root->right && root->val == target) ? nullptr : root;
    }
};