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
.
/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: void visitNode(TreeNode *root, int prevSum, int &sum) { if (root == NULL) { return; } if (root->left == NULL && root->right == NULL) { sum += 10*prevSum + root->val; return; } if (root->left) { visitNode(root->left, 10*prevSum + root->val, sum); } if (root->right) { visitNode(root->right, 10*prevSum + root->val, sum); } } int sumNumbers(TreeNode *root) { int sum = 0; visitNode(root, 0, sum); return sum; } };