版权声明:本文为自学而写,如有错误还望指出,谢谢^-^ https://blog.csdn.net/weixin_43871369/article/details/89715609
题目描述
Given a binary tree containing digits from0-9only, each root-to-leaf path could represent a number.
An example is the root-to-leaf path1->2->3which represents the number123.
Find the total sum of all root-to-leaf numbers.
For example,
1
/ \
2 3
The root-to-leaf path1->2represents the number12.
The root-to-leaf path1->3represents the number13.
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:
int sumNumbers(TreeNode *root) {
if(root==nullptr) return 0;
int sum=0;
return pre(root,sum);
}
private:
int pre(TreeNode *ptr,int sum)
{
if(ptr==nullptr) return 0;
sum=ptr->val+sum*10;
if(ptr->left==nullptr&&ptr->right==nullptr)
return sum;
return pre(ptr->left,sum)+pre(ptr->right,sum);
}
};