剑指offer-树的子结构

/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
/*
输入两棵二叉树A，B，判断B是不是A的子结构。（ps：我们约定空树不是任意一个树的子结构）
*/
public class Solution {
    public boolean HasSubtree(TreeNode root1,TreeNode root2) {
        if(root1==null || root2==null) return false;
        return fun(root1,root2)||fun(root1.left,root2)||fun(root1.right,root2);
    }
    public boolean fun(TreeNode node1, TreeNode node2) {
        if(node2 == null) return true;
        else if(node1 == null) return false;
        else if(node1.val != node2.val) return false;
        return fun(node1.left,node2.left)&&fun(node1.right,node2.right);
    }
}