Q:
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"]
A:
/** * 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) { vector<string> res; if (root==NULL) return res; binaryTreePaths(res, root, to_string(root->val)); return res; } void binaryTreePaths(vector<string>& result, TreeNode* node, string s) { if (node->left==NULL && node->right==NULL) { result.push_back(s); return; } if (node->left) binaryTreePaths(result, node->left, s + "->" + to_string(node->left->val)); if (node->right) binaryTreePaths(result, node->right, s + "->" + to_string(node->right->val)); } };
