leetCode(36):Sum Root to Leaf Numbers 分类： leetCode 2015-07-13 16:00 157人阅读 评论(0) 收藏

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:
void sumNumber(TreeNode* root, int sum,int& result)
{
if (root == NULL) return;//直接返回

sum = sum * 10 + root->val;

if (root->left == NULL && root->right == NULL)
{//相加求和返回
result += sum;
return;
}

sumNumber(root->left, sum,result);
sumNumber(root->right, sum,result);
}

int sumNumbers(TreeNode* root) {
int result = 0;
sumNumber(root, 0, result);
return result;
}
};