LC_669_TrimBST.cpp

/*
https://leetcode.com/problems/trim-a-binary-search-tree/
669. Trim a Binary Search Tree

*/

/**
 * 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* trimBST(TreeNode* root, int low, int high) {
        
        if(!root) return root;
        
        root->left = trimBST(root->left, low, high);
        root->right = trimBST(root->right, low, high);
        
        
        if(root->val < low)
            return root->right;
        else if(root->val > high)
            return root->left;
        
        return root;
        
        
    }// end
};