题解 | #二叉搜索树的最近公共祖先#深度优先简单处理

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) {
        if (root == null) {
            return -1;
        }
        if (p > q) {
            int temp = p;
            p = q;
            q = temp;
        }

        return dfs(root, p, q);
    }

    public int dfs(TreeNode root, int left, int right) {
        if (null == root) {
            return -1;
        }
        if (root.val > left && root.val > right) {
            return dfs(root.left, left, right);
        } else if (root.val < left && root.val < right) {
            return dfs(root.right, left, right);
        }
        return root.val;
    }

}