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.
递归求解，注意中间变量与全局变量的保存。
1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 void getSum(TreeNode *root, int &sum, int val) { 13 if (root->right == NULL && root->left == NULL) { 14 sum += val; 15 return; 16 } 17 if (root->left != NULL) { 18 getSum(root->left, sum, val * 10 + root->left->val); 19 } 20 if (root->right != NULL) { 21 getSum(root->right, sum, val * 10 + root->right->val); 22 } 23 } 24 25 int sumNumbers(TreeNode *root) { 26 if (root == NULL) { 27 return 0; 28 } 29 int sum = 0; 30 getSum(root, sum, root->val); 31 return sum; 32 } 33 };
[Leetcode] Sum Root to Leaf Numbers,布布扣,bubuko.com
[Leetcode] Sum Root to Leaf Numbers
原文：http://www.cnblogs.com/easonliu/p/3631333.html