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"]

/**
* 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> result;
vector<int> buf;

visit(root, buf, result);

return result;
}
private:
void visit(TreeNode *root, vector<int> &buf, vector<string> &result)
{
if (root == NULL)
{
return;
}

buf.push_back(root->val);
if (root->left == NULL && root->right == NULL)
{
string cur;
char temp[10];
sprintf(temp, "%d", buf[0]);
cur += temp;
for (int i = 1; i < buf.size(); i++)
{
sprintf(temp, "%d", buf[i]);
cur += "->";
cur += temp;
}
result.push_back(cur);
}
else
{
visit(root->left, buf, result);
visit(root->right, buf, result);
}
buf.pop_back();
}
};