判断一棵树是否是搜索二叉树、判断一棵树是否是完全二叉树

 

package my_basic.class_4;

import java.util.Stack;

import class_04.Code_07_IsBSTAndCBT.Node;

public class Code_07_IsSBTAndCBT {
    public static class Node{
        int value;
        Node left;
        Node right;
        public Node(int value) {
            this.value = value;
        }
    }

    /**判断是否是搜索二叉树
     * 中序遍历 有序 
     * @return
     */
    public static Boolean isSBT(Node head) {
        if (head != null) {
            Stack<Node> stack = new Stack<Node>();
            int pre = Integer.MIN_VALUE;
            while (!stack.isEmpty() || head!=null) {
                if (head!=null) {
                    stack.add(head);
                    head = head.left;
                }else {
                    head = stack.pop();
//                    System.out.print(head.value+" ");
                    if (head.value < pre) {
                        return false;
                    }
                    pre = head.value;
                    head = head.right;
                }
            }
        }
        return true;
    }
    
    public static void main(String[] args) {
        Node head = new Node(4);
        head.left = new Node(2);
        head.right = new Node(6);
        head.left.left = new Node(1);
        head.left.right = new Node(3);
        head.right.left = new Node(5);

        System.out.println(isSBT(head));
    }
}