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
     */
    public int lowestCommonAncestor (TreeNode root, int p, int q) {
        // write code here
		//参考视频 https://www.bilibili.com/video/BV1Zt4y1F7ww/?spm_id_from=333.337.search-card.all.click&vd_source=b70998ab4c3dc381a8a392ec5c30c541
        TreeNode node = diedai(root, p, q);
        return node.val;

    }

    // 递归法
    public TreeNode digui(TreeNode node, int p, int q) {
        if (node == null) {
            return null;
        }
        if (p < node.val && q < node.val) {
            node = node.left;
        }
        if (p > node.val && q > node.val) {
            node = node.right;
        }
        return node;
    }

    // 迭代法
    public TreeNode diedai(TreeNode node, int p, int q) {

        if (node == null) {
            return null;
        }
        while (node != null) {
            if (p < node.val && q < node.val) {
                node = node.left;
            }
            if (p > node.val && q > node.val) {
                node = node.right;
            }
            break;
        }

        return node;
    }






}