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
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 =
» Solve this problem25
.[Thoughts]
Recursion. Similar as [LeetCode] Binary Tree Maximum Path Sum Solution, the difference here is only adding a track variable to sum all the paths.
[Code]
1: int sumNumbers(TreeNode *root) {
2: int sum=0, path =0;
3: GenerateSum(root, sum, path);
4: return sum;
5: }
6: void GenerateSum(TreeNode *root, int& sum, int path)
7: {
8: if(root == NULL) return;
9: path = path*10 +root->val;
10: if(root->left == NULL && root->right == NULL)
11: {
12: sum+=path;
13: return;
14: }
15: GenerateSum(root->left, sum, path);
16: GenerateSum(root->right, sum, path);
17: }
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