path-sum-ii

class Solution {
public:
    vector<vector<int>>ans;
    vector<int>path;
    vector<vector<int> > pathSum(TreeNode *root, int sum) {
        if(root)dfs(root,sum);
        return ans;
    }
    void dfs(TreeNode*root,int sum)
    {
        path.push_back(root->val);
        sum-=root->val;
        if(!root->left&&!root->right&&sum==0)
        {
            ans.push_back(path);
            path.pop_back();
            return;
        }
        if(root->left)dfs(root->left,sum);
        if(root->right)dfs(root->right,sum);
        path.pop_back();
    }
};

class Solution {
public:
    vector<vector<int>>ans;
    vector<int>path;
    vector<vector<int> > pathSum(TreeNode *root, int sum) {
        if(root)dfs(root,sum);
        return ans;
    }
    void dfs(TreeNode*root,int sum)
    {
        path.push_back(root->val);
        sum-=root->val;
        if(!root->left&&!root->right&&sum==0)
            ans.push_back(path);
        else
        {
            if(root->left)dfs(root->left,sum);
            if(root->right)dfs(root->right,sum);
        }
        path.pop_back();
    }
};