14
08/2015
[LeetCode] Sum Root to Leaf Numbers
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
.
解题思路:
这道题的意思是每条从根到叶的数字组成一个数,然后所有的数加起来。
一个好的办法就是递归。
/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: int sumNumbers(TreeNode* root) { int result = 0; helper(root, 0, result); return result; } void helper(TreeNode* root, int temp, int& result){ if(root==NULL){ return; } temp = temp*10; temp = temp + root->val; if(root->left==NULL && root->right==NULL){ result += temp; } helper(root->left, temp, result); helper(root->right, temp, result); } };
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