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【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
.
每到达一个根节点,就代表一个路径访问完成,将和加入总和。
树结构用递归是最容易的,每递归一层,上层的部分和需要乘以10在做加法。
/** * Definition for binary tree * 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 Sum = 0; Helper(root, 0, Sum); return Sum; } void Helper(TreeNode* root, int partSum, int& Sum) { if(root == NULL) return; else if(root->left == NULL && root->right == NULL) //add this path Sum += (10*partSum+root->val); else { Helper(root->left, 10*partSum+root->val, Sum); Helper(root->right, 10*partSum+root->val, Sum); } }};
【LeetCode】Sum Root to Leaf Numbers
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