题解 | #二叉搜索树的最近公共祖先#

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param root TreeNode类
     * @param p int整型
     * @param q int整型
     * @return int整型
     */
    int  pre = -1;
    public int lowestCommonAncestor (TreeNode root, int p, int q) {
        // write code here
        int m = p>q?q:p;
        int n = p>q?p:q;
        inorder(root, m, n);
        return pre;
        
    }
    public void inorder(TreeNode root, int p, int q){
        if(root == null){
            return;
        if(root.val>p&&root.val<q){
            pre = root.val;
            return;
        if(root.val==p||root.val==q){
            pre = root.val;
            return;
        if(root.val<p){
            inorder(root.right,p,q);
        if(root.val>q){
            inorder(root.left,p,q);
        }
    }
}