nnn.cpp

用链表计算任意大小数的阶乘

//计算任意大小阶乘	
//于鑫 2004.7 Visual C++ 6.0 & Windows XP环境调试通过//
//-------------------------------------------------------------
#include "iostream.h"
#include "fstream.h"
#include "stdlib.h"
//-------------------------------------------------------------
//定义一个链表
class Node
{
private:
	int data;
	Node *next;
	Node *prev;
	Node *head;
	Node *rear;
public:
	Node(const int& item)
	:data(item),prev(NULL),next(NULL),head(NULL),rear(NULL){};
	//获得下一个节点
	Node* GetNextNode(){return next;};
	//获得上一个节点
	Node* GetPrevNode(){return prev;};
	//插入
	void InsertAfterMe(Node* p);
	//删除所有指定
	void DeleteMe(void);
	int GetData(void){return data;};
	void SetData(int item){data = item;};
	//重置
	Node* GoBacktoHead();
	//跳到后面
	Node* GoForwardtoRear();
	//全不清除
	void ClearAll(void);
	//获得链的计数
	int GetElementNum();
};

int Node::GetElementNum()
{
	int count = 0;
	Node* p =GoBacktoHead();
	while(p->GetNextNode()!=NULL)
	{ 
		count++;
		p = p->GetNextNode();
	}
	count++;
	return count;
}

void Node::InsertAfterMe(Node* p)
{
	// Node* p;
	if(prev == NULL) 
	{ 
		head = this;
	}
	p->next = next;
	p->prev = this;
	next = p;
	if(p->next == NULL) 
	{
		rear = p;
	}
};

void Node::DeleteMe(void)
{
	if(prev == NULL) // 如果是第一个节点
	{ 
		next->prev = NULL;
		head = next;  // 那么下一个节点变为第一个
		delete this;  //删除此节点
		return;
	}
	if(next == NULL)//如果是最后一个节点
	{  
		prev->next = NULL;
		rear = prev; // 那么上一个节点变为最后一个
		return;
	}
	prev->next = next;
	delete this;
};

Node* Node::GoBacktoHead()
{
	if(head == this)//如果是第一个节点
	{ 
		return this;
	}
	Node *p = this;
	while(p->prev != NULL)
	{
		p = p->prev;
	}
	return p;
}

Node* Node::GoForwardtoRear()
{
	if(rear == this)
	{
		return this;
	}
	Node *p = this;
	while(p->next != NULL)
	{
		p = p->next;
	}
	return p;
}

void Node::ClearAll(void)
{
	Node* p = GoBacktoHead();
	Node* p2;
	while(p->GetNextNode() != NULL)
	{
		p2 = p;
		p = p->GetNextNode();
		delete p2;
	}
	delete p;
};
//--------------------------------------------------
//主程序开始
int main(void)
{
Codebegin:
	int remain;//余数
	int carry;//进位
	int result;//结果
	int N;//输入的待机算数
	char filename[20];//保存结果的文件名
	Node* p = new Node(1);
	cout<<"请输入一个任意大小的非负整数:";
	cin>>N;
	cout<<"请输入存储计算结果的文件名:";
	cin>>filename;
	cout<<"正在计算"<<N<<"的阶乘，请稍等...";
	ofstream fout (filename);
	for(int n=1;n<=N;n++)
	{
		cout<<".";
		remain = carry = 0;
		p = p->GoBacktoHead();
		//一个一个处理元素,直到链尾
		while(p->GetNextNode() != NULL)
		{
			result = p->GetData()*n+carry;
			if(result>=10)
			{
				remain = result%10;
				carry = result/10;
				p->SetData(remain);
			}
			else
			{
				p->SetData(result);
			}
			p = p->GetNextNode();
			carry = result/10;
		}
		result = p->GetData()*n+carry;
		//如果产生进位,处理进位并存入新分配的空间
		while(result >= 10)
		{
			Node * newNode = new Node(0);
			p->SetData(result%10);//余数
			result = result/10;
			p->InsertAfterMe(newNode);
			p = p->GetNextNode();
		}
		p->SetData(result);
	}
	p = p->GoForwardtoRear();
	fout<<"本软件由于鑫于2004年7月制作,用于计算任意大小阶乘.\n\n";
	fout<<"--------------------------------------------------------------------\n";
	fout<<"\n您要计算"<<N<<"的阶乘(注意'==>'符号后的部分为计算结果的科学技术形式).\n\n结果如下:";
	fout<<"\n\n"<<N<<"!=";
	cout<<"\n\n"<<N<<"!=";
	while(p->GetPrevNode()!=NULL)
	{
		fout<<p->GetData();
		cout<<p->GetData();
		p=p->GetPrevNode();
	}
	fout<<p->GetData();//输出结果写入文件
	cout<<p->GetData();//输出结果
	int num;
	num=p->GetElementNum();
	if(num>=5)
	{
		p = p->GoForwardtoRear();
		fout<<"==>"<<p->GetData()<<".";
		cout<<"==>"<<p->GetData()<<".";
		p = p->GetPrevNode();
		for(int i=1;i<5;i++)
		{
			fout<<p->GetData();
			cout<<p->GetData();
			p = p->GetPrevNode();
		}
		fout<<"E"<<num-1<<"\n";//科学技术形式写入文件
		cout<<"E"<<num-1<<"\n";//输出结果的科学技术形式
	}
	fout.close();//关闭文件
	//释放内存
	p->ClearAll();
	char ch;
	cout<<"是否继续?(Y=是/N=否):";
	cin>>ch;
	if (ch=='Y'||ch=='y') goto Codebegin;
	return 0;
}
//程序结束
//------------------------------------------------------------------