34.cpp

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution
{
  private:
    void pathSum(TreeNode *root, int target, vector<int> cur, vector<vector<int>> &res)
    {
        cur.push_back(root->val);
        target -= root->val;
        if (!root->left && !root->right && !target)
            res.push_back(cur);
        if (root->left)
            pathSum(root->left, target, cur, res);
        if (root->right)
            pathSum(root->right, target, cur, res);
        return;
    };

  public:
    vector<vector<int>> pathSum(TreeNode *root, int target)
    {
        vector<int> cur;
        vector<vector<int>> res;
        if (root)
            pathSum(root, target, cur, res);
        return res;
    }
};