1.3 求任意整數降序數

/********************************
*
*		c++程序設計實踐指導
*
*		1.3求任意整數降序數
*
*********************************/

#include <iostream>
using namespace std;
class NUM
{
	struct LinkNode
	{
		int key;
		LinkNode *Next;
	};
	long long n;		//存放整數
	LinkNode *head;		//單鏈表表頭節點
public:
	NUM(long long x)		//構造函數，用x初始化n；
	{
		n = x;
		int w = 0;
		while(n)
		{
			n = n / 10;
			++w;
		}
		head = new LinkNode;
		LinkNode *p = head;		
		p->key = 0;
		for(int i = 0; i < w-1; i++)
		{
			LinkNode *q = new LinkNode;
			q->key = 0;
			p->Next = q;
			p = q;
		}
		p->Next = NULL;
		n = x;
	}
	void decrease();		//完成降序排列的功能
	void expect();		//按最大、最小、次最大、次最小等間隔排列
	void show()		//在屏幕顯示功能
	{
		int sumn = 0;
		LinkNode *p = head;
		cout << "the number is : " << n << endl; 
		cout << "we change it to : ";
		while(p)
		{
			cout << p->key;
			sumn += p->key;
			p = p->Next;
		}
		cout << endl;
		cout << "Sum of every number is :" << sumn << endl;
	}
};
void NUM::decrease()		//降序
{
	long long k;		//k存放整數值
	int temp;		//臨時存放替換元素值
	k = n;
	LinkNode *p = head;
	while(p)		//將整數分解存入單鏈表中
	{
		p->key = k % 10;
		k = k / 10;
		p = p->Next;
	}
	p = head;
	while(p->Next)		//新建指針q爲p的下指針位置，比較p和q的鍵值，指針q依次向後移，完了以後p後移一位，q爲p的下指針位置
	{
		LinkNode *q = new LinkNode;
		q = p->Next;
		while(q)
		{
			if(q->key > p->key)		//大的鍵值前移
			{
				temp = q->key;
				q->key = p->key;
				p->key = temp;
			}
			q = q->Next;
		}
		p = p->Next;
		q = p->Next;		
	}
}
void NUM::expect()		//最大、最小、次最大、次最小的順序
{
	long long k;		//k存放整數值
	int temp;		//臨時存放替換元素值
	k = n;
	LinkNode *p = head;
	while(p)		//將整數分解存入單鏈表中
	{
		p->key = k % 10;
		k = k / 10;
		p = p->Next;
	}
	p = head;
	LinkNode *q = new LinkNode;
	while(p->Next && p->Next->Next)
	{
		q = p->Next;
		while(q)		//p指針後最大的鍵值前移
		{
			if(q->key > p->key)
			{
				temp = q->key;
				q->key = p->key;
				p->key = temp;
			}
			q = q->Next;
		}
		p = p->Next;
		q = p->Next;
		while(q)		//p指針後最小的鍵值前移
		{
			if(q->key < p->key)
			{
				temp = q->key;
				q->key = p->key;
				p->key = temp;
			}
			q = q->Next;
		}
		p = p->Next;
		q = p->Next;
	}
	if(p->Next)		//結束前判斷是否剩餘一對鍵值爲比較
	{
		if(q->key > p->key)
		{
			temp = q->key;
			q->key = p->key;
			p->key = temp;
		}
	}
}
int main()
{
	long long m;
	cout << "please enter some number : " << endl;
	cin >> m;
	cout << endl;
	NUM nx(m);
	nx.decrease();
	nx.show();
	cout << endl;
	nx.expect();
	nx.show();
	system("pause");
	return 0;
}