Leetcode-标签为Tree 257. Binary Tree Paths

原题

Given a binary tree, return all root-to-leaf paths.

For example, given the following binary tree:

   1 /   \2     3 \  5All root-to-leaf paths are:["1->2->5", "1->3"]

题目分析

求二叉树的所有路径，输出路径图。递归求解。

代码实现

        public IList<string> BinaryTreePaths(TreeNode root)        {            if (root == null)                return new List<string>();            if (root.left == null && root.right == null)                return new List<string> { root.val.ToString() };            IList<string> rtn = new List<string>();            IList<string> rtnleft =  BinaryTreePaths(root.left);//左子树路径            foreach(var item in rtnleft)//左子树都继承于根节点                rtn.Add(root.val + "->" + item);            IList<string> rtnright = BinaryTreePaths(root.right);            foreach (var item in rtnright)                rtn.Add(root.val + "->" + item);            return rtn;        }

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