1353. Sum Root to Leaf Numbers

Description

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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.

A leaf is a node with no children.

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Example

Example:

Input: [1,2,3]
    1
   / \
  2   3
Output: 25
Explanation:
The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.
Therefore, sum = 12 + 13 = 25.

Example 2:

Input: [4,9,0,5,1]
    4
   / \
  9   0
 / \
5   1
Output: 1026
Explanation:
The root-to-leaf path 4->9->5 represents the number 495.
The root-to-leaf path 4->9->1 represents the number 491.
The root-to-leaf path 4->0 represents the number 40.
Therefore, sum = 495 + 491 + 40 = 1026.

class Solution { public: /** * @param root: the root of the tree * @return: the total sum of all root-to-leaf numbers */ int sumNumbers(TreeNode * root) { // write your code here int sum = 0; int path = 0; dfs(root, sum, path); return sum; } void dfs(TreeNode *root, int &sum, int path){ if(root->left == NULL && root->right == NULL){ path += root->val; sum += path; return; } path += root->val; if(root->left != NULL){ dfs(root->left, sum, path*10); } if(root->right != NULL){ dfs(root->right, sum, path*10); } } };