Binary Trees2-Path Sum Root to Leaf

For a given Binary Tree of type integer and a number K, print out all root-to-leaf paths where the sum of all the node data along the path is equal to K.
Example:
alt txt

If you see in the above-depicted picture of Binary Tree, we see that there are a total of two paths, starting from the root and ending at the leaves which sum up to a value of K = 13.

The paths are:
a. 2 3 4 4
b. 2 3 8

One thing to note here is, there is another path in the right sub-tree in reference to the root, which sums up to 13 but since it doesn't end at the leaf, we discard it.
The path is: 2 9 2(not a leaf)
 Input Format:
The first line of input will contain the node data, all separated by a single space. Since -1 is used as an indication whether the left or right node data exist for root, it will not be a part of the node data.

The second line of input contains an integer value K.
Output Format:
Lines equal to the total number of paths will be printed. All the node data in every path will be printed in a linear fashion taken in the order they appear from top to down bottom in the tree. A single space will separate them all.
Constriants:
1 <= N <= 10^5
0 <= K <= 10^8
Where N is the total number of nodes in the binary tree.

Time Limit: 1 second
Sample Input 1:
2 3 9 4 8 -1 2 4 -1 -1 -1 6 -1 -1 -1 -1 -1
13
 Sample Output 1:
2 3 4 4 
2 3 8
Sample Input 2:
5 6 7 2 3 -1 1 -1 -1 -1 9 -1 -1 -1 -1
13
 Sample Output 2:
5 6 2
5 7 1

*********************************************Solution**************************************

public static void rootToLeafPathsSumToK(BinaryTreeNode<Integer> root, int k) {
		
		String arr="";
		rootToLeafPathsSumToK(root, k,arr);
	}
  
	private static void rootToLeafPathsSumToK(BinaryTreeNode<Integer> root, int k, String arr) 
	{
		if(root==null)
			return;
		int rootData=root.data;
		arr=arr+rootData+" ";
		if(k==rootData && root.left==null && root.right==null)
		{
			System.out.println(arr);
			return;
		}
		rootToLeafPathsSumToK(root.left, k-rootData,arr);
		rootToLeafPathsSumToK(root.right, k-rootData,arr);
    
	}