257. 二叉树的所有路径

https://leetcode-cn.com/problems/binary-tree-paths/

Java

/*
 * @Author: Goog Tech
 * @Date: 2020-08-16 17:00:50
 * @LastEditTime: 2020-08-16 17:11:57
 * @Description: https://leetcode-cn.com/problems/binary-tree-paths/
 * @FilePath: \leetcode-googtech\#102. Binary Tree Level Order Traversal\257.二叉树的所有路径.java
 * @WebSite: https://algorithm.show/
 */

/*
 * @lc app=leetcode.cn id=257 lang=java
 *
 * [257] 二叉树的所有路径
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {

    public List<String> binaryTreePaths(TreeNode root) {
        LinkedList<String> paths = new LinkedList<>();
        getPaths(root, "", paths);
        return paths;
    }

    private void getPaths(TreeNode root, String path, LinkedList<String> paths) {
        if(root !=null) {
            // 记录当前节点到叶子节点的路径
            path += Integer.toString(root.val);
            // 判断当前节点是否为叶子节点,若是则将其整体添加到 List 集合中
            if(root.left == null && root.right == null) {
                paths.add(path);
            // 反之则继续遍历当前节点的左右孩子节点
            }else {
                path += "->";
                getPaths(root.left, path, paths);
                getPaths(root.right, path, paths);
            }
        }
    }
}
// @lc code=end

Python

'''
Author: Goog Tech
Date: 2020-08-16 16:58:35
LastEditTime: 2020-08-16 17:10:50
Description: https://leetcode-cn.com/problems/binary-tree-paths/
FilePath: \leetcode-googtech\#102. Binary Tree Level Order Traversal\257.二叉树的所有路径.py
WebSite: https://algorithm.show/
'''
#
# @lc app=leetcode.cn id=257 lang=python
#
# [257] 二叉树的所有路径
#

# @lc code=start
# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def binaryTreePaths(self, root):
        """
        :type root: TreeNode
        :rtype: List[str]
        """
        # 判断当前节点是否为空
        if not root: 
            return []
        # 判断当前节点是否为叶子节点
        if not root.left and not root.right: 
            return [str(root.val)]
        # 初始化用于存储根节点到左右叶子节点路径的列表
        paths = []
        # 递归添加当前节点到叶子节点的路径
        if root.left:
            for i in self.binaryTreePaths(root.left):
                paths.append(str(root.val) + '->' + i)
        if root.right:
            for i in self.binaryTreePaths(root.right):
                paths.append(str(root.val) + '->' + i)
        # 返回结果
        return paths
# @lc code=end