二叉树中和为某一值的路径

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};*/
class Solution {
public:
    vector<vector<int>>res;
    void findpath(TreeNode* root,int val,int sum,vector<int>& path)
        {
        if(root==NULL)
            return ;
        sum+=root->val;
        path.push_back(root->val);
        bool isleaf=false;
        if(root->left==NULL&&root->right==NULL)
            isleaf=true;
        if(sum==val&&isleaf)
            res.push_back(path);
        if(root->left)
            findpath(root->left,val,sum,path);
        if(root->right)
            findpath(root->right,val,sum,path);
        path.pop_back();
        
    }
    vector<vector<int> > FindPath(TreeNode* root,int expectNumber) {
      if(root==NULL) return res;
     vector<int> path;
        int sum=0;
        findpath(root,expectNumber,sum,path);
        return res;
        
    }
};