先来先服务(FCFS)算法

快期末了在复习操作系统，顺便把实验课上写的算法重新写一遍

先来先服务算法非常简单，当作业来了，先来先运行，后来的按到达时间的先后排在就绪队列上，每次取队首元素运行。

实验环境是WIN7 64位+Visual Studio 2015

//main.cpp
#include "FCFS.h"

int main()
{
	std::vector PCBList;

	//输入作业信息
	InputPCB(PCBList);

	//FCFS算法
	FCFS(PCBList);

	//显示结果
	show(PCBList);

	return 0;
}

//FCFS.h
#ifndef FCFS_H_
#define FCFS_H_

#include 
#include 
#include 
#include 

//作业结构体
typedef struct PCB
{
	int ID;							//标识符
	int ComeTime;					//到达时间
	int ServerTime;					//服务时间
	int FinishTime;					//完成时间
	int TurnoverTime;				//周转时间
	double WeightedTurnoverTime;	//带权周转时间
}PCB;

/*
函数功能：输入作业信息
参数说明：
PCBList		std::vector&		PCB链
*/
void InputPCB(std::vector &PCBList);

/*
函数功能：FCFS算法
参数说明：
PCBList		std::vector&		PCB链
*/
void FCFS(std::vector &PCBList);

/*
函数功能：显示结果
参数说明：
PCBList		std::vector&		PCB链
*/
void show(std::vector &PCBList);

/*
函数功能：比较函数，用于sort()，按ComeTime升序排列
参数说明：
p1			const PCB&				PCB
p2			const PCB&				PCB
*/
bool cmp(const PCB &p1, const PCB &p2);

#endif

//FCFS.cpp
#include "FCFS.h"

void InputPCB(std::vector &PCBList)
{
	do {
		PCB temp;
		std::cout << "输入标识符: ";
		std::cin >> temp.ID;
		std::cout << "输入到达时间: ";
		std::cin >> temp.ComeTime;
		std::cout << "输入服务时间: ";
		std::cin >> temp.ServerTime;
		PCBList.push_back(temp);

		std::cout << "继续输入？Y/N: ";
		char ans;
		std::cin >> ans;
		if ('Y' == ans || 'y' == ans)
			continue;
		else
			break;
	} while (true);
}

void FCFS(std::vector &PCBList)
{
	std::sort(PCBList.begin(), PCBList.end(), cmp);		//按升序排列ComeTime
	int FinishTime = -1;								//上一个作业的完成时间
	for (std::vector::iterator it = PCBList.begin(); it < PCBList.end(); ++it)
	{
		if ((*it).ComeTime < FinishTime)				//作业到达时，上一个作业还没有结束
			(*it).FinishTime = (*(it - 1)).FinishTime + (*it).ServerTime;
		else
			(*it).FinishTime = (*it).ComeTime + (*it).ServerTime;
		(*it).TurnoverTime = (*it).FinishTime - (*it).ComeTime;
		(*it).WeightedTurnoverTime = (double)(*it).TurnoverTime / (*it).ServerTime;
		FinishTime = (*it).FinishTime;
	}
}

void show(std::vector &PCBList)
{
	int SumTurnoverTime = 0;
	double SumWeightedTurnoverTime = 0;

	std::cout.setf(std::ios::left);

	std::cout << std::setw(20) << "标识符";
	for (std::vector::iterator it = PCBList.begin(); it < PCBList.end(); ++it)
		std::cout << std::setw(5) << (*it).ID;
	std::cout << std::endl;

	std::cout << std::setw(20) << "到达时间";
	for (std::vector::iterator it = PCBList.begin(); it < PCBList.end(); ++it)
		std::cout << std::setw(5) << (*it).ComeTime;
	std::cout << std::endl;

	std::cout << std::setw(20) << "服务时间";
	for (std::vector::iterator it = PCBList.begin(); it < PCBList.end(); ++it)
		std::cout << std::setw(5) << (*it).ServerTime;
	std::cout << std::endl;

	std::cout << std::setw(20) << "完成时间";
	for (std::vector::iterator it = PCBList.begin(); it < PCBList.end(); ++it)
		std::cout << std::setw(5) << (*it).FinishTime;
	std::cout << std::endl;

	std::cout << std::setw(20) << "周转时间";
	for (std::vector::iterator it = PCBList.begin(); it < PCBList.end(); ++it)
	{
		std::cout << std::setw(5) << (*it).TurnoverTime;
		SumTurnoverTime += (*it).TurnoverTime;;
	}
	std::cout << std::endl;

	std::cout << std::setw(20) << "带权周转时间";
	for (std::vector::iterator it = PCBList.begin(); it < PCBList.end(); ++it)
	{
		std::cout << std::setw(5) << (*it).WeightedTurnoverTime;
		SumWeightedTurnoverTime += (*it).WeightedTurnoverTime;;
	}
	std::cout << std::endl;

	std::cout << "平均周转时间: " << (double)SumTurnoverTime / PCBList.size() << std::endl;
	std::cout << "平均带权周转时间: " << SumWeightedTurnoverTime / PCBList.size() << std::endl;
}

bool cmp(const PCB &p1, const PCB &p2)
{
	return p1.ComeTime < p2.ComeTime;
}