leetcode_c++:树:Sum Root to Leaf Numbers(129)

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.

class Solution {
private:
int sum;
void dfs(TreeNode *cur, int num) {
num = num * 10 + cur->val;
if (!cur->left && !cur->right) {
sum += num;
return;
}
if (cur->left)
dfs(cur->left, num);
if (cur->right)
dfs(cur->right, num);
}
public:
int sumNumbers(TreeNode *root) {
if (!root)
return 0;
sum = 0;
dfs(root, 0);
return sum;
}
};