【LeetCode】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

.

思路：重新构建了一个函数，返回值是每一个节点的权值和该节点的val。递归即可。

/**
* Definition for binary tree
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
struct LNodenum{
int val;
int lev;
};
class Solution {
public:
LNodenum cacul(TreeNode *root){
LNodenum ret;
ret.val=0;
ret.lev=1;
if(root==NULL)return ret;
if(root->left==NULL&&root->right==NULL){
ret.val=root->val;
return ret;
}else if(root->left==NULL){
ret=cacul(root->right);
ret.lev*=10;
ret.val+=root->val*ret.lev;
return ret;
}else if(root->right==NULL){
ret=cacul(root->left);
ret.lev*=10;
ret.val+=root->val*ret.lev;
return ret;
}else{
ret=cacul(root->left);
LNodenum ret1=cacul(root->right);
ret.lev=(ret.lev+ret1.lev)*10;
ret.val=root->val*ret.lev+ret.val+ret1.val;
return ret;
}
}
int sumNumbers(TreeNode *root) {
LNodenum ret=cacul(root);
return ret.val;
}
};