Sum Root to Leaf Numbers

LeetCode 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.

深度优先搜索：

//将动态数组中的单个数数转换成整数
int vecToInt(vector<int>& v)
{
	int sum = 0;
	for(int i=0; i<v.size(); i++)
	{
		sum += (pow(10, v.size()-1-i)*v[i]);
	}

	return sum;
}

void pathSum(TreeNode* p, vector<int>& sub_sum, int & sum)
{
	//如果是叶节点，则计算出动态数组中的数字，计入sum中
	if(p->left==NULL && p->right==NULL)
	{
		sub_sum.push_back(p->val);
		sum = sum + vecToInt(sub_sum);
		return ;
	}
	
	sub_sum.push_back(p->val);
	if(p->left!=NULL)
	{
		pathSum(p->left, sub_sum, sum);
		sub_sum.pop_back();
	}

	if(p->right!=NULL)
	{
		pathSum(p->right, sub_sum, sum);
		sub_sum.pop_back();
	}
}

int sumNumbers(TreeNode *root) 
{
	if(root==NULL)
		return 0;

	vector<int> sub_sum;
	int sum = 0;

	pathSum(root, sub_sum, sum);
	return sum;
}