LintCode脸书面经真题+解析+代码：二叉树的所有路径

描述

给一棵二叉树，找出从根节点到叶子节点的所有路径。

在线评测地址：LintCode 炼码Powerful coding training system. LintCode has the most interview problems covering Google, Facebook, Linkedin, Amazon, Microsoft and so on. We provide Chinese and English versions for coders around the world.https://www.lintcode.com/problem/1746/?utm_source=sc-csdn-mwy

免费查询LintCode/LeetCode答案：

https://www.jiuzhang.com/problem/?utm_source=sc-csdn-mwy

样例1

输入：{1,2,3,#,5}
输出：["1->2->5","1->3"]
解释：
   1
 /   \
2     3
 \
  5

样例 2

输入：{1,2}
输出：["1->2"]
解释：
   1
 /   
2  

解题思路

使用分治算法(Divide Conquer)

源代码

// version 1: Divide Conquer
public class Solution {
    /**
     * @param root the root of the binary tree
     * @return all root-to-leaf paths
     */
    public List<String> binaryTreePaths(TreeNode root) {
        List<String> paths = new ArrayList<>();
        if (root == null) {
            return paths;
        }
        
        List<String> leftPaths = binaryTreePaths(root.left);
        List<String> rightPaths = binaryTreePaths(root.right);
        for (String path : leftPaths) {
            paths.add(root.val + "->" + path);
        }
        for (String path : rightPaths) {
            paths.add(root.val + "->" + path);
        }
        
        // root is a leaf
        if (paths.size() == 0) {
            paths.add("" + root.val);
        }
        
        return paths;
    }
}

更多题解参考：https://www.jiuzhang.com/solution/binary-tree-paths/?utm_source=sc-csdn-mwy

标签：paths,List,mwy,LintCode,经真题,二叉树,path,root
来源： https://blog.csdn.net/hsvdh/article/details/123578682