Solution.java

import java.util.*;

public class Solution
{
    public List<List<Integer>> pathSum(TreeNode root, int sum)
    {
        List<List<Integer>> paths = new ArrayList<>();
        getPaths(root, sum, new ArrayList<Integer>(), paths);
        return paths;
    }

    private void getPaths(TreeNode root, int sum, ArrayList<Integer> arrayList, List<List<Integer>> paths)
    {
        if (root == null)
        {
            return;
        }
        arrayList.add(root.val);
        if (sum == root.val && root.left == null && root.right == null)
        {
            paths.add(arrayList);
            return;
        }
        getPaths(root.left, sum - root.val, new ArrayList<>(arrayList), paths);
        getPaths(root.right, sum - root.val, new ArrayList<>(arrayList), paths);
    }

    public class TreeNode
    {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode(int x)
        {
            val = x;
        }
    }
}