Leetcode 669 Solution

This article provides solution to leetcode question 669 (trim-a-binary-search-tree)
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https://leetcode.com/problems/trim-a-binary-search-tree

Solution

/**
 * 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* trimBST(TreeNode* root, int L, int R) {
        if (root == NULL)
            return NULL;

        if (root->val < L)
            return trimBST(root->right, L, R);
        else if (root->val > R)
            return trimBST(root->left, L, R);
        else
        {
            root->left = trimBST(root->left, L, R);
            root->right = trimBST(root->right, L, R);
            return root;
        }
    }
};