package weblab;

import java.util.*;

class Solution {

  /**
   * Computes whether the BinaryTree is a binary search tree.
   *
   * @param tree
   *     the BinaryTree to check.
   * @return true iff the BinaryTree is a binary search tree, else false.
   */
  public static boolean isTreeBST(BinaryTree tree) {
    return bst(tree, Integer.MIN_VALUE,
                               Integer.MAX_VALUE);
  }

  public static boolean bst(BinaryTree tree, int min, int max){
  // TODO
  if(tree == null){
    return true;
  }
  if(tree.getKey() < min || tree.getKey() > max){
    return false;
  }

  return bst(tree.getLeft(), min, tree.getKey() - 1) && bst(tree.getRight(), tree.getKey()+1, max);
  }
}