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
.
思路:
对二叉树进行递归搜索,同时记录迄今为止得到的值,当碰到叶结点的时候,就将这个值加在已知的和上。
题解:
/** * 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 Sum; void TraverseProc(const TreeNode* node, int value) { const int VAL = value * 10 + node->val; if (node->left == nullptr && node->right == nullptr) Sum += VAL; // at a leaf else { if (node->left != nullptr) TraverseProc(node->left, VAL); if (node->right != nullptr) TraverseProc(node->right, VAL); } } int sumNumbers(TreeNode *root) { Sum = 0; if (root != nullptr) TraverseProc(root, 0); return Sum; } };