Sum Root to Leaf Numbers

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

An example is the root-to-leaf path 1->2->3 which represents the number 123.

Find the total sum of all root-to-leaf numbers.

For example,

    1   / \  2   3

The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.

Return the sum = 12 + 13 = 25.

由于加到和里面的值跟其所处节点的层数有关系，所以需要记录这一信息，这里用了一个vector来存，因为顺序代表着以一种层次关系。然后用一个全局的sum来累加。

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:   int sum = 0;void sums(TreeNode*root,vector<int>vec){if (!root)return;vec.push_back(root->val);if (!root->left && !root->right){int count = vec.size()-1;for (auto i : vec){sum += pow(10.0,count)*i;--count;}return;}sums(root->left,vec);sums(root->right,vec);}int sumNumbers(TreeNode* root){vector<int>vec;sums(root,vec);return sum;}};