Method checkBST

java/Chapter 4/Question4_5/QuestionB.java:7–19

(TreeNode n, Integer min, Integer max)

public class QuestionB {
	public static boolean checkBST(TreeNode n, Integer min, Integer max) {
		if (n == null) {
			return true;
		}
		if ((min != null && n.data <= min) || (max != null && n.data > max)) {
			return false;
		}
		if (!checkBST(n.left, min, n.data) ||
			!checkBST(n.right, n.data, max)) {
			return false;
		}
		return true;
	}
		
	public static boolean checkBST(TreeNode n) {
		return checkBST(n, null, null);