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.
简单的用递归就可以实现，代码如下：
1 class Solution { 2 public: 3 int sumNumbers(TreeNode* root) { 4 if(!root) return 0; 5 dfs(root, 0); 6 } 7 8 int dfs(TreeNode * root, int curr){ 9 if(!root->left && !root->right) return curr; 10 if(!root->left && root->right) return dfs(root->right, curr * 10); 11 if(root->left && !root->right) return dfs(root->left, curr * 10); 12 else return dfs(root->left, curr * 10) + dfs(root->right, curr * 10); 13 } 14 private: 15 int sum; 16 };
LeetCode OJ：Sum Root to Leaf Numbers（根到叶节点数字之和）
原文：http://www.cnblogs.com/-wang-cheng/p/4910721.html