BinaryTreePaths.java

package tree;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by gouthamvidyapradhan on 09/12/2017. Given a binary tree, return all root-to-leaf paths.
 *
 * <p>For example, given the following binary tree:
 *
 * <p>1 / \ 2 3 \ 5 All root-to-leaf paths are:
 *
 * <p>["1->2->5", "1->3"]
 */
public class BinaryTreePaths {

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

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

  public List<String> binaryTreePaths(TreeNode root) {
    List<String> result = new ArrayList<>();
    new BinaryTreePaths().inorder(root, result, "");
    return result;
  }

  private void inorder(TreeNode node, List<String> list, String path) {
    if (node != null) {
      if (node.left == null && node.right == null) {
        list.add(path + node.val);
      } else {
        inorder(node.left, list, path + node.val + "->");
        inorder(node.right, list, path + node.val + "->");
      }
    }
  }
}