LeetCode257——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"]

实现：

/**
 * 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> vs;
        if (root == NULL) return vs;
        if (root->left == NULL && root->right == NULL) {
            char buff[124];
            sprintf(buff, "%d", root->val);
            vs.push_back(buff);
            return vs;
        }
        if (root->left) {
            vector<string> lefts = binaryTreePaths(root->left);
            for (int i = 0; i < lefts.size(); i++) {
                char *buff = new char[lefts[i].size()+56];
                sprintf(buff, "%d->%s", root->val, lefts[i].c_str());
                vs.push_back(buff);
                delete[] buff;
            }
        }
        if (root->right) {
            vector<string> rights = binaryTreePaths(root->right);
            for (int i = 0; i < rights.size(); i++) {
                char *buff = new char[rights[i].size()+56];
                sprintf(buff, "%d->%s", root->val, rights[i].c_str());
                vs.push_back(buff);
                delete[] buff;
            }
        }
        return vs;
    }
};