LeetCode:Sum Root to Leaf Numbers

题目描述：

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.

代码：

int get_number(vector
  
    vec)
{
    int length = vec.size();
    int n = 0;
    int factor = 1;
    for(int i = length-1;i >= 0;i--)
    {
        n = n + factor * vec[i];
        factor = factor * 10;
    }
    return n;
}

int calculate(vector
   
     vec,TreeNode *treeNode) { if(treeNode->left == NULL && treeNode->right == NULL) { vec.push_back(treeNode->val); return get_number(vec); } else if(treeNode->left != NULL && treeNode->right == NULL) { vec.push_back(treeNode->val); return calculate(vec,treeNode->left); } else if(treeNode->left == NULL && treeNode->right != NULL) { vec.push_back(treeNode->val); return calculate(vec,treeNode->right); } else if(treeNode->left != NULL && treeNode->right != NULL) { vec.push_back(treeNode->val); return calculate(vec,treeNode->left) + calculate(vec,treeNode->right); } } int Solution::sumNumbers(TreeNode *root) {
   
  

    if（root == NULL）

	return 0;

    vector
  
    vec;
    return calculate(vec,root);
}