进程调度模拟程序设计
题目简单来说，就是模拟按优先数调度算法实现处理器调度的程序，详细题目如下：
进程调度模拟程序设计题目
做这个题目，比较方便的是用链表，而进程可以用如下结构体表示：
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| struct PCB{
int name;
PCB *next;
int time;
int prior;
int status;
};
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在插入的时候，我们先按照大小查找到要插入的位置，即该节点(进程)的优先级比该位置的要大，就插入到该位置的前面：
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| int PCBlist::insert(PCB p)
{
PCB *a = new PCB;
a->name = p.name;
a->time = p.time;
a->prior = p.prior;
a->status = p.status;
if(!head->next)
{
head->next = a;
a->next = nullptr;
}
else
{
PCB *b = head->next;
PCB *c = head;
for(; b; )
{
if(a->prior >= b->prior)
{
c->next = a;
a->next = b;
break;
}
c = c->next;
b = b->next;
if(!b)
{
c->next = a;
a->next = nullptr;
}
}
}
return 0;
}
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所以在初始化中，我们就得到了一条完整的按照优先级排列的进程链表，我们只需要每次取出队首的进程，执行(优先级和时间-1)，然后把它从这个链表中拿出，再重新按照优先级插入即可。当运行时间为0时，我们就可以不再重新插入它，而是直接输出状态为E，表示执行完毕：
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| int run(PCBlist &T)
{
PCB *a = T.head;
PCB *ne;
a->next->time = a->next->time - 1;
a->next->prior = a->next->prior - 1;
ne = a->next;
cout << "此时正在运行P" << ne->name << "程序" << endl;
cout << "程序的运行时间还剩" << ne->time << endl;
a->next = ne->next;
if(ne->time)
T.insert(*ne);
else{
cout << "进程P" << ne->name << "运行结束" << endl;
cout << "------------------------------" << endl;
cout << "进程名：P" << ne->name << ' ';
cout << "优先级：" << ne->prior << ' ';
cout << "剩余运行时间：" << ne->time << ' ';
cout << "状态：E" << endl;
cout << "------------------------------" << endl;
}
return 0;
}
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在每次run，也就是每次执行一个进程时，我们将链表输出，以查看当时的所以未执行完的进程的状态：
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| int PCBlist::show()
{
PCB *a = head->next;
for(; a; a = a->next)
{
cout << "------------------------------" << endl;
cout << "进程名：P" << a->name << ' ';
cout << "优先级：" << a->prior << ' ';
cout << "剩余运行时间：" << a->time << ' ';
cout << "状态：R" << endl;
cout << "------------------------------" << endl;
}
return 0;
}
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| while(T.head->next)
{run(T);
T.show();}
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下面放上全部的代码和执行结果：
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| #include <iostream>
using namespace std;
struct PCB{
int name;
PCB *next;
int time;
int prior;
int status;
};
class PCBlist
{
public:
PCB *head;
PCBlist();
int insert(PCB p);
int show();
};
PCBlist::PCBlist()
{
head = new PCB;
head->next = nullptr;
}
int PCBlist::insert(PCB p)
{
PCB *a = new PCB;
a->name = p.name;
a->time = p.time;
a->prior = p.prior;
a->status = p.status;
if(!head->next)
{
head->next = a;
a->next = nullptr;
}
else
{
PCB *b = head->next;
PCB *c = head;
for(; b; )
{
if(a->prior >= b->prior)
{
c->next = a;
a->next = b;
break;
}
c = c->next;
b = b->next;
if(!b)
{
c->next = a;
a->next = nullptr;
}
}
}
return 0;
}
int run(PCBlist &T)
{
PCB *a = T.head;
PCB *ne;
a->next->time = a->next->time - 1;
a->next->prior = a->next->prior - 1;
ne = a->next;
cout << "此时正在运行P" << ne->name << "程序" << endl;
cout << "程序的运行时间还剩" << ne->time << endl;
a->next = ne->next;
if(ne->time)
T.insert(*ne);
else{
cout << "进程P" << ne->name << "运行结束" << endl;
cout << "------------------------------" << endl;
cout << "进程名：P" << ne->name << ' ';
cout << "优先级：" << ne->prior << ' ';
cout << "剩余运行时间：" << ne->time << ' ';
cout << "状态：E" << endl;
cout << "------------------------------" << endl;
}
return 0;
}
int PCBlist::show()
{
PCB *a = head->next;
for(; a; a = a->next)
{
cout << "------------------------------" << endl;
cout << "进程名：P" << a->name << ' ';
cout << "优先级：" << a->prior << ' ';
cout << "剩余运行时间：" << a->time << ' ';
cout << "状态：R" << endl;
cout << "------------------------------" << endl;
}
return 0;
}
int main() {
PCBlist T;
int n = 1;
PCB a;
int time;
int prior;
int status;
for(; n < 6; n++)
{
a.name = n;
cout << "请输入第" << n << "个进程的运行时间：" ;
cin >> time;
a.time = time;
cout << "请输入第" << n << "个进程的优先级：" ;
cin >> prior;
a.prior = prior;
a.status = 1;
T.insert(a);
}
cout << "------------------------------" << endl;
while(T.head->next)
{run(T);
T.show();}
return 0;
}
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完