操作系统实验：首次适应算法、最佳适应算法、最坏适应算法

#include <iostream>
using namespace std;

#define FREE 0
#define  BUSY 1
#define  MAX_length 300
const double debri = 20; //设置碎片大小
// FREE代表空闲  BUSY代表已分配 

typedef struct free_area //首先定义空闲区分表结构
{
int flag;
int size;
int number;
int begin_address;
 }Elemtype;
 
typedef struct Free_Node
{
	Elemtype date;
	struct Free_Node *prior;
	struct Free_Node *next;
}Free_Node,*pNod;
 
pNod headNode;
pNod initNode;
int m_allocation();//作业分配
int free(int number);//作业回收
bool ff(int number,int size);//首次适应算法
void show();//查看分配
void init();//初始化

int main()
{
	int tag=0;
	int number;
	init();
	while(tag!=4)
	{
		cout<<"请选择操作： 1-申请作业，2-作业回收，3-显示作业状况，4-退出"<<endl;
		cin>>tag;
		switch(tag)
			{
		    case 1:
				m_allocation();
				    break;
			case 2:
				cout<<"请输入需要回收的number号："<<endl;
				cin>>number;
				free(number);
					break;
			case 3:
				show();
				break;
			default:
				return 0;
		    }
	}
	return 0;
}

void init()
{
	headNode=new Free_Node;
	initNode = new Free_Node;
	headNode->prior=NULL;
	headNode->next=initNode;
	initNode->prior=headNode;
	initNode->next=NULL;
	initNode->date.begin_address=0;
	initNode->date.flag=FREE;
	initNode->date.number= 0;
	initNode->date.size=MAX_length;
}
 
//实现作业分配
int m_allocation()
{
	int number,size1;
	cout<<"请输入作业号：";
	cin>>number;
	cout<<"请输入所需作业大小：";
	cin>>size1;

	if(ff(number,size1))
	{		
		cout<<"分配成功！"<<endl;
	}
	else cout<<"分配失败！"<<endl;
	return 1;
}
 
bool ff(int number,int size)//首次适应算法
{
	 pNod temp= new Free_Node;
	 Free_Node *p=headNode->next;  //从首节点开始
	 temp->date.number=number;
	 temp->date.size=size;
	 temp->date.flag=BUSY;
	while(p)
	{
		if (p->date.flag==FREE &&  p->date.size == size )//请求大小刚好满足
		{
			p->date.flag=BUSY;
			p->date.number=number;
			return true;
		}
		if (p->date.flag==FREE && p->date.size>size)//说明还有其他的空闲区间
		{
			temp->next=p;
			temp->prior=p->prior;
			temp->date.begin_address=p->date.begin_address;
			p->prior->next=temp;
			p->prior=temp;
			p->date.begin_address=temp->date.begin_address+temp->date.size;//空闲分区开始地址+此次分配的空间
			p->date.size-=size;      //分配空闲作业
		    return true;
		}
		p=p->next;
	}
	return false;
}

int free(int number)//主存回收
{
	Free_Node *p=headNode->next;
	while(p)
	{
		if (p->date.number==number)//找到要回收的number区域
		{
			p->date.flag=FREE;
			p->date.number=FREE;
			//判断P与前后区域关系

			//1、回收分区r上临一个空闲分区，此时应该合并为一个连续的空闲区，其始址为r上相邻的分区的首地址，而大小为两者大小之和
			if (p->prior->date.flag==FREE&&p->next->date.flag!=FREE)   
			{
				p->prior->date.size+=p->date.size;
				p->prior->next=p->next;  //将要回收分区的前后两个分区链接起来
				p->next->prior=p->prior;
			}
			//2、回收分区r与下相邻空闲分区，合并后仍然为空闲区，该空闲区的始址为回收分区r的地址。大小为两者之和
			else if (p->prior->date.flag!=FREE&&p->next->date.flag==FREE)
			{
				p->date.size+=p->next->date.size;   //合并前后两个分区
				if(p->next->next)      //下一个分区不是最后一个分区
				{
					p->next->next->prior=p;
				    p->next = p->next->next;
				}
				else 
					p->next=p->next->next;
			}
			//3、回收部分r与上下空闲区相邻，此时将这三个区域合并，始址为r上相邻区域的地址，大小为三个分区大小之和
			else if(p->prior->date.flag==FREE&&p->next->date.flag==FREE)
			{
				p->prior->date.size+=p->date.size+p->next->date.size;
				if(p->next->next) //如果最后一个节点不是最后一个节点
				{
				p->next->next->prior=p->prior;
				p->prior->next=p->next->next;
				}
				else p->prior->next=p->next->next;
			}
			//4、当回收部分r上下区域都为非空闲区域，此时建立一个新的空闲分区，并且加入到空闲区队列中去
			else if(p->prior->date.flag!=FREE && p->next->date.flag!=FREE)
			{
				//只用把结点的number和flag改成free就行了
			}
			break;
		}
		p=p->next;
	}
	cout<<"回收成功！"<<endl;
	return 1;
}

void show()
{
	cout<< endl;
	cout<<"作业分配情况"<<endl;
	int i = 1;
	Free_Node *p=headNode->next;
	cout<<"分区号"  << "  作业号" << "\t起始地址"  << "    作业大小"  << "   分区状态" << endl;
	while(p)
	{
		cout << i++ << "\t " << p->date.number << '\t' << p->date.begin_address << "\t\t" << p->date.size << '\t';
		if (p->date.flag==FREE)
			cout<<"空闲"<<endl;
		else
			 cout<<"已分配"<<endl;
		p=p->next;
	}
}

#include <iostream>
#include <stdlib.h>
using namespace std;
 
#define FREE 0
#define  BUSY 1
#define  MAX_length 300
 
typedef struct freeArea
{
	int flag;
	int size;
	int ID;
	int address;
}Elemtype;
 
typedef struct Free_Node
{
	Elemtype date;
	struct Free_Node *front;
	struct Free_Node *next;
}Free_Node,*FNodeList;
 
FNodeList block_first;
FNodeList block_last;
int alloc(int tag);//内存分配
int free(int ID);//内存回收
int best_fit(int ID,int size);//最佳适应算法
void show();//查看分配
void init();//初始化
void menu();

//初始化 
void init()
{
	block_first=new Free_Node;
	block_last = new Free_Node;
	block_first->front=NULL;
	block_first->next=block_last;
	block_last->front=block_first;
	block_last->next=NULL;
	block_last->date.address=0;
	block_last->date.flag=FREE;
	block_last->date.ID=FREE;
	block_last->date.size=MAX_length;
}
 
//实现内存分配
int alloc(int tag)
{
	int ID,size1;
	cout<<"请输入作业号：";
	cin>>ID;
	cout<<"请输入所需内存大小：";
	cin>>size1;
	if (ID<=0 || size1<=0)
	{
		cout<<"ERROR,请输入正确的ID和请求大小"<<endl;
		return 0;
	}
	
	if (tag==1)//采用最佳适应算法
	{
		if (best_fit(ID,size1))
		{
			cout<<"分配成功！"<<endl;
		}
		else cout<<"分配失败！"<<endl;
		return 1;
	}
	
}
 
int best_fit(int ID,int size)//最佳适应算法
{
	int surplus;//记录可用内存与需求内存的差值
	FNodeList temp=(FNodeList)malloc(sizeof(Free_Node));
	Free_Node *p=block_first->next;
	temp->date.ID=ID;
	temp->date.size=size;
	temp->date.flag=BUSY;
	Free_Node *q=NULL;//记录最佳位置
	while(p)//遍历链表，找到第一个可用的空闲区间将他给q
	{
		if (p->date.flag==FREE&&p->date.size>=size)
		{
			q=p;
			surplus=p->date.size-size;
			break;
		}
		p=p->next;
	}
	while(p)//继续遍历，找到更加合适的位置
	{
		if (p->date.flag==FREE&&p->date.size==size)
		{
			p->date.flag=BUSY;
			p->date.ID=ID;
			return 1;
			break;
		}
		if (p->date.flag==FREE&&p->date.size>size)
		{
			if (surplus>p->date.size-size)
			{
				surplus=p->date.size-size;
				q=p;
			}
 
		}
		p=p->next;
	}
	if (q==NULL)//如果没有找到位置
	{
		return 0;
	}
	else//找到了最佳位置
	{
		temp->next=q;
		temp->front=q->front;
		temp->date.address=q->date.address;
		q->front->next=temp;
		q->front=temp;
		q->date.size=surplus;
		q->date.address+=size;
		return 1;
	}
}
 
int free(int ID)//主存回收
{
	Free_Node *p=block_first->next;
	while(p)
	{
		if (p->date.ID==ID)//找到要回收的ID区域
		{
			p->date.flag=FREE;
			p->date.ID=FREE;
			//判断P与前后区域关系
			if (p->front->date.flag==FREE&&p->next->date.flag!=FREE)
			{
				p->front->date.size+=p->date.size;
				p->front->next=p->next;
				p->next->front=p->front;
			}
			if (p->front->date.flag!=FREE&&p->next->date.flag==FREE)
			{
				p->date.size+=p->next->date.size;
				if(p->next->next)
				{
					p->next->next->front=p;
				p->next = p->next->next;
				}
				else p->next=p->next->next;
			}
			if(p->front->date.flag==FREE&&p->next->date.flag==FREE)
			{
				p->front->date.size+=p->date.size+p->next->date.size;
				if(p->next->next)
				{
				p->next->next->front=p->front;
				p->front->next=p->next->next;
				}
				else p->front->next=p->next->next;
			}
			if(p->front->date.flag!=FREE&&p->next->date.flag!=FREE)
			{//
				
			}
			break;
		}
		p=p->next;
	}
	cout<<"回收成功！"<<endl;
	return 1;
}



void show()
{
	cout<< endl;
	cout<<"作业分配情况"<<endl;
	int i = 1;
	Free_Node *p=block_first->next;
	cout<<"分区号"  << "  作业号" << "\t起始地址"  << "    作业大小"  << "   分区状态" << endl;
	
	while(p)
	{
		cout << i++ << "\t " << p->date.ID << '\t' << p->date.address << "\t\t" << p->date.size << '\t';
		if (p->date.flag==FREE)
			cout<<"空闲"<<endl;
		else
			cout<<"已分配"<<endl;
		p=p->next;
	}
	
}

void menu()//菜单
{
	int tag=0;
	int ID;
	init();
	cout<<"分区模拟："<<endl;
	while(tag!=4)
	{
		cout<<"请输入要进行的操作："<<endl;
		cout<<"1-申请作业，2-作业回收，3-显示作业状况，4-退出"<<endl;
			cin>>tag;
		switch(tag)
			{
			case 1:
				alloc(tag);
				break;
			case 2:
				cout<<"请输入需要回收的ID号："<<endl;
				cin>>ID;
				free(ID);
				break;
			case 3:
				show();
				break;
		    }
	}
 
}
int main()
{
	menu();
}