gistfile1.java

isSorted(root,Integer.MIN_VALUE,Integer.MAX_VALUE);

public static boolean isSorted(Node cur, int min, int max) {
  if (cur==null) {
    return true;
  } else if (cur.val < min || cur.val > max) {
    return false;
  } else {
    boolean sorted = true;
    if (cur.left != null && cur.left.val > cur.val) {
        sorted = false;
    }
    if (cur.right != null && cur.right.val < cur.val) {
        sorted = false;
    }
    return sorted && isSorted(cur.left,min,cur.val) && isSorted(cur.right,cur.val,max);

  }
}

/**
 * The second base case is for the case
 *        5
 *    4       7
 *  3  6     6 8
 * 
 * Which would pass without it, but is technically incorrect based on the definition.
 **/