前序遍历递归

class Solution {
public:
vector<vector<int> > FindPath(TreeNode* root, int expectNumber) {
vector<vector<int> > res;
vector<int> tem;
int n = 0;
fun(res, tem, root, expectNumber, 0);
return res;
}
void fun(vector<vector<int> > &res, vector<int> tem, TreeNode *root, int expectNumber, int nowNum)
{
if (root==NULL)
{
return;
}
tem.push_back(root->val);
nowNum = nowNum + root->val;
if (nowNum > expectNumber)
{
return;
}
if (nowNum == expectNumber && root->left == NULL && root->right == NULL)
{
res.push_back(tem);
return;
}</int></int></int></int></int>

    fun(res, tem, root->left, expectNumber, nowNum);
    fun(res, tem, root->right, expectNumber, nowNum);
    return;

}

};