剑指offer 树的子结构

public class Solution {
    public boolean HasSubtree(TreeNode root1,TreeNode root2) {
        if(root1==null || root2==null){
            return false;
        }
        boolean rs=false;
        if(isSubTree(root1,root2)||isSubTree(root1.left,root2)||isSubTree(root1.right,root2)){
            rs=true;
        }
        return rs;
    }
    public boolean isSubTree(TreeNode root1,TreeNode root2){
        if(root2==null){
            return true;
        }
        if(root1==null){
            return false;
        }
        if(root1.val==root2.val){
            return (isSubTree(root1.left,root2.left) && isSubTree(root1.right,root2.right));
        }else{
            return false;
        }
    }
}