LeetCode 235.二叉搜索树的最近公共祖先

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

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if(root==null||root==p||root==q){
                return root;
        }
        //p,q  的值都比根结点大，那么就从右子树找
        if(p.val<root.val&&q.val<root.val){
            return lowestCommonAncestor(root.left,p,q);
        }
        //p,q  的值都比根结点小，那么就从左子树找
        if(p.val>root.val&&q.val>root.val){
            return lowestCommonAncestor(root.right,p,q);
        }
        //找不到就在根结点上
        return root;
    }
}