Binary Tree Paths

Given a binary tree, return all root-to-leaf paths.

For example, given the following binary tree:

 

   1
 /   \
2     3
 \
  5

 

All root-to-leaf paths are:

["1->2->5", "1->3"]

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
	List<String> res = new ArrayList<>();
    public List<String> binaryTreePaths(TreeNode root) {
        if (root != null) {
        	findPaths(root, String.valueOf(root.val));
        }
        return res;
    }
	private void findPaths(TreeNode root, String valueOf) {
		// TODO Auto-generated method stub
		if (root.left == null && root.right == null) {
			res.add(valueOf);
		}
		if (root.left != null) {
			findPaths(root.left, valueOf + "->" + root.left.val);
		}
		if (root.right != null) {
			findPaths(root.right, valueOf + "->" + root.right.val);
		}
	}
}