题解 | #在二叉树中找到两个节点的最近公共祖先#

using System;
using System.Collections.Generic;

/*
public class TreeNode
{
	public int val;
	public TreeNode left;
	public TreeNode right;

	public TreeNode (int x)
	{
		val = x;
	}
}
*/

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 o1 int整型 
     * @param o2 int整型 
     * @return int整型
     */
    public int lowestCommonAncestor (TreeNode root, int o1, int o2) {
        if(root == null) return -1;
        if(root.val == o1 || root.val == o2) return root.val;
        int left = lowestCommonAncestor(root.left, o1, o2);
        int right = lowestCommonAncestor(root.right, o1, o2);
        if(left == -1) {
            if(right == -1) return -1;
            return right;
        }
        if(right == -1) return left;
        return root.val;
    }
}