Sum Root to Leaf Numbers 根节点到叶子组成数的和

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

.

/**
 * 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:
    int sumNumbers(TreeNode* root) {
        
        return solve(root,0);
    }
    
    int solve(TreeNode *root,int sum)
    {
        if(root==NULL)
        {
            return 0;
        }
        if(root->left==NULL&&root->right==NULL)
        {
           return sum*10+root->val;
        }
        return solve(root->left,sum*10+root->val)+solve(root->right,sum*10+root->val);
    }
};