leetcode[129]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 binary tree
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
void dfs(int &sum, int num, TreeNode *root)
{
if(root==NULL)return;
num+=root->val;
if(root->left==NULL&&root->right==NULL)
{
sum+=num;
return;
}
if(root->left)dfs(sum, 10*num, root->left);
if(root->right)dfs(sum, 10*num, root->right);
}
int sumNumbers(TreeNode *root) {
int sum=0;
int num=0;
dfs(sum, num, root);
return sum;
}
};