LeetCode[Tree]: Sum Root to Leaf Numbers
來源:程序員人生 發(fā)布時間:2014-12-13 08:49:10 閱讀次數(shù):3739次
Given a binary tree containing digits from 0⑼ 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.
這個題目很簡單,可用遞歸做:
class Solution {
public:
int sumNumbers(TreeNode *root) {
sum = 0;
sumNumbers(root, 0);
return sum;
}
private:
int sum;
void sumNumbers(TreeNode *root, int num) {
if (!root) return;
num = num*10 + root->val;
if (root->left == nullptr && root->right == nullptr) sum += num;
if (root->left) sumNumbers(root->left, num);
if (root->right) sumNumbers(root->right, num);
}
};
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