LeetCode-Binary Tree Paths -解题报告

原题链接 https://leetcode.com/problems/binary-tree-paths/

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

For example, given the following binary tree:

   1 /   \2     3 \  5

All root-to-leaf paths are:

["1->2->5", "1->3"]

打印出到叶子节点的路径。

dfs就行了，还有一点就是value可能是负数。

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:vector<string> binaryTreePaths(TreeNode* root) {flag = false;dfs(root, "");return ans;}void dfs(TreeNode* root, string path){if (root == NULL)return;if (root->left == NULL && root->right == NULL){if (!flag)flag = true;else path += "->";ans.push_back(path + iTos(root->val));return;}if (!flag)flag = true;else path += "->";path += iTos(root->val);dfs(root->left, path);dfs(root->right, path);}string iTos(int& val){bool flag = true;if (val < 0)flag = false, val = -val;string str = "";while (val){str = (char((val % 10) + '0')) + str;val /= 10;}if (!flag)str = "-" + str;return str;}private:bool flag;vector<string>ans;};