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; }