剑指offer26 树的子结构 Java

public class SubTreeConstruct26_ {
    static class Node {
        int val;
        Node left;
        Node right;
        public Node(int val){
            this.val = val;
        }
        @Override
        public String toString() {
            return "Node{" +
                    "val=" + val +
                    ", left=" + left +
                    ", right=" + right +
                    '}';
        }
    }

    public static void main(String[] args) {
        Node root = new Node(8);
        Node node02 = new Node(8);
        Node node03 = new Node(7);
        Node node04 = new Node(9);
        Node node05 = new Node(2);
        Node node06 = new Node(4);
        Node node07 = new Node(7);
        root.left = node02;
        root.right = node03;
        node02.left = node04;
        node02.right = node05;
        node05.left = node06;
        node05.right = node07;

        Node sub = new Node(8);
        System.out.println(isSub(root, sub));
    }

    private static boolean isSub(Node root, Node sub) {
        boolean result = false;
        if (root != null && sub != null) {
            if (root.val == sub.val) {
                result = isSub2(root, sub);
            }
            if (!result) {
                result = isSub(root.left, sub);
            }
            if (!result) {
                result = isSub(root.right, sub);
            }
        }
        return result;
    }

    private static boolean isSub2(Node root, Node sub) {
        if (root == null)
            return false;
        if (sub == null)
            return true;
        if (root.val != sub.val)
            return false;
        return isSub2(root.left, sub.left) && isSub2(root.right, sub.right);
    }
}