235. Lowest Common Ancestor of a Binary Search Tree

class Solution {
public:
    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
		if(!root) return NULL;
 		if(!p) return q;
 		if(!q) return q;
		
		TreeNode *r = root;
		int mini = min(p->val, q->val);
		int maxi = max(p->val, q->val);
		while(r){
			if(mini <= r->val && maxi >= r->val)
				return r;
			else if(mini > r->val)
				r = r->right;
			else 
				r = r->left;	
		}	
		return NULL;	
    }
};