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Lowest Common Ancestor of a Binary Search Tree

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Description

https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/description/

Solution

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/**
 * 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* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
        if (root == NULL) return NULL;
        if ( (root->val <= p->val && root->val >= q->val) || 
             (root->val <= q->val && root->val >= p->val)) return root;
        
        if (root->val < p->val) return lowestCommonAncestor(root->right, p, q);
        return lowestCommonAncestor(root->left, p, q);
    }
    
};