LeetCode之sum root to leaf numbers

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Sum Root to Leaf NumbersFeb 192554 / 7177

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.

Run Status: Accepted!
Program Runtime: 8 milli secs

/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {

private:
void traceTree(TreeNode *root, int number, int &sum)
{
if(NULL == root)
return;
if(NULL == root->left && NULL == root->right)
{
number *= 10;
number += root->val;
sum += number;
return;
}
if(root->left != NULL)
{
traceTree(root->left, number*10+root->val, sum);
}
if(root->right != NULL)
{
traceTree(root->right, number*10+root->val, sum);
}
}
public:
int sumNumbers(TreeNode *root) {
// Start typing your C/C++ solution below
// DO NOT write int main() function

if(NULL == root)
return 0;
int sum = 0, number=0;

number = root->val;
if(NULL == root->left && NULL == root->right)
return number;
if(root->left)
traceTree(root->left, number, sum);
if(root->right)
traceTree(root->right, number, sum);

return sum;
}
};

测试用例：

{}00  
{0}00  
{9}99  
{0,1}11  
{0,1,3}44  
{1,0}1010  
{2,0,0}4040  
{1,#,5}1515  
{1,2,3}2525  
{4,9,0,#,1}531531