Leetcode & CTCI ---Day 4

Path Sum II

 Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5
             / \
            4   8
           /   / \
          11  13  4
         /  \    / \
        7    2  5   1

return

[
   [5,4,11,2],
   [5,8,4,5]
]
This problem is kind of similar but harder that the path sum I proglem. And I firstly just use a very brutal force solution. I print out all the path from root to leaf in the tree, and then I check each path's sum. If that equals to expected sum, keep it. Else 

public ArrayList<ArrayList<Integer>> pathSum(TreeNode root, int sum) {
           if (root == null)
                return null;
           ArrayList<Integer> path = new ArrayList<Integer>();
           ArrayList<ArrayList<Integer>> resultList = new ArrayList<ArrayList<Integer>>();
           resultList = getAllPath(root, path, resultList);
           //printResult(resultList);
           return filterResultList(resultList, sum);
           //return null;
    }
    
    public ArrayList<ArrayList<Integer>> getAllPath(TreeNode root, ArrayList<Integer> path, ArrayList<ArrayList<Integer>> resultList ){
        if (root == null)
            return null;
        path.add(root.val);
        if (root.left == null && root.right == null){
            //System.out.println(path);
            resultList.add(path);
            return resultList;
        }
        getAllPath(root.left, new ArrayList<Integer>(path), resultList);
        getAllPath(root.right, new ArrayList<Integer>(path), resultList);
        return resultList;
    }
        
    public ArrayList<ArrayList<Integer>> pathSum(TreeNode root, ArrayList<ArrayList<Integer>> resultList){
        if (root == null)
            return null;
            
        resultList.get(resultList.size()-1).add(root.val);
        
        if (root.left != null){
            ArrayList<ArrayList<Integer>> tempList = resultList;
            tempList = pathSum(root.left, tempList);
        }
        if (root.right != null){
            ArrayList<Integer> nestList = resultList.get(resultList.size()-1);
            resultList.add(nestList);
            resultList = pathSum(root.right, resultList);
        }
        return resultList;
    }
    
    public ArrayList<ArrayList<Integer>> filterResultList(ArrayList<ArrayList<Integer>> resultList, int sum){
        for (int i = 0; i < resultList.size(); i ++){
            int realSum = 0;
            for (int element: resultList.get(i)){
                realSum += element;
                //System.out.println(element);
            }
            if (realSum != sum)
                resultList.remove(i);
        }
        return resultList;
    }
    
    public void printResult(ArrayList<ArrayList<Integer>> resultList){
        for (ArrayList<Integer> nestResult : resultList){
            for (int element : nestResult){
                System.out.print(element + " ");
            }
            System.out.println("");
        }
    }
    
    public class TreeNode {
              int val;
              TreeNode left;
              TreeNode right;
              TreeNode(int x) { val = x; }
          }
    
    public static void main(String[] args){
        solution obj = new solution();
        
        TreeNode h = obj.new TreeNode(1);
        TreeNode a = obj.new TreeNode(-2);
        TreeNode b = obj.new TreeNode(-3);
        TreeNode c = obj.new TreeNode(1);
        TreeNode d = obj.new TreeNode(3);
        TreeNode f = obj.new TreeNode(1);
        TreeNode e = obj.new TreeNode(3);
        
        h.left = a;
        h.right = b;
        a.left = c;
        a.right = d;
        c.left = f;
        b.left = e;
        //obj.pathSum(h, 2);
        obj.printResult(obj.pathSum(h, 1));
    }