Given a binary tree, find all paths that sum of the nodes in the path equals to a given numbertarget.

A valid path is from root node to any of the leaf nodes.

Example

Given a binary tree, and target =5:

     1
    / \
   2   4
  / \
 2   3

return

[
  [1, 2, 2],
  [1, 4]
]

/**

* Definition of TreeNode:

* public class TreeNode {

* public int val;

* public TreeNode left, right;

* public TreeNode(int val) {

* this.val = val;

* this.left = this.right = null;

* }

* }

*/

public class Solution {
/\*\*

 \* @param root the root of binary tree

 \* @param target an integer

 \* @return all valid paths

 \*/

public List<List<Integer>> binaryTreePathSum(TreeNode root, int target) {

    // Write your code here

    List<List<Integer>> result = new ArrayList<List<Integer>>();

    List<Integer> list = new ArrayList<Integer>();

    if (root == null) {

        return result;

    }



    helper(root, target, result, list);

    return result;

}



private void helper(TreeNode root, int target, List<List<Integer>> result, List<Integer> list) {

    if (root.left == null && root.right == null) {

        if (target == root.val) {

            list.add(root.val);

            result.add(new ArrayList(list));

            list.remov(list.size() - 1);

        }

        return;

    }

    list.add(root.val);

    helper(root.left,target - root.val, result, list);

    helper(root.right,target - root.val, result, list);

    list.remove(list.size() - 1);

}
}