树的子结构

#include<iostream>
using namespace std;

struct treenode
{
    char data;
    treenode *lchild;
    treenode *rchild;
};
bool issame(treenode *head1,treenode *head2);
//先序构建二叉树（递归）
treenode *init()
{
    treenode *head=new treenode;
    char data;
    cout<<"please input a number of node<按#结束>"<<endl;
    cin>>data;
    if(data==‘#‘)
        return NULL;
    else
    {
        head->data=data;
        head->lchild=init();
        head->rchild=init();
    }
    return head;
}
//先序打印二叉树
void preorderprint(treenode *head)
{
    if(head)
    {
        cout<<head->data<<"    ";
        preorderprint(head->lchild);
        preorderprint(head->rchild);
    }
}
//判断第二个树是否为第一个树的子结构
bool contains(treenode *head1,treenode *head2)
{
    bool result=false;
    //空树是任何树的子结构
    if(head2==NULL)
        return true;
    if(head1!=NULL)
    {
        //如果两个结点相等，则继续判断他们的子树是否相等
        if(head1->data==head2->data)
            result=issame(head1,head2);
        //如果不是子树，递归判断左子树
        if(!result)
            result=contains(head1->lchild,head2);
        //如果不是子树，递归判断右子树
        if(!result)
            result=contains(head2->rchild,head2);
    }
    return result;
}
//递归判断两个结点的子树是否也相同
bool issame(treenode *head1,treenode *head2)
{
    //如果第二个结点为空，则返回true
    if(head2==NULL)
        return true;
    //第一个节点为空，则返回false
    if(head1==NULL)
        return false;
    //如果两个结点都不为空并且他们不相等，返回false
    if(head1->data!=head2->data)
        return false;
    //两个结点相等则递归判断他们左右子树的结点是否相等
    return issame(head1->lchild,head2->lchild)&&issame(head1->rchild,head2->rchild);
}

int main()
{
    treenode *head1=init();
    preorderprint(head1);
    cout<<endl;
    treenode *head2=init();
    preorderprint(head2);
    cout<<endl;
    cout<<"是否包含："<<contains(head1,head2);
    return 0;
}