题意 模拟程序并行运行
STL队列 双端队列 的应用 用双端队列维护即将执行的程序 再用个队列维护等待变量释放的程序 用lock表示变量锁定状态
先将所有程序依次放到执行队列中 每次取出队首程序运行不超过lim时间 未运行完又放到执行队列队尾
遇到lock时 若当前锁定状态为false就将锁定状态变为true 否则将当前程序放到等待队列队尾并结束运行
遇到unlock时 若等待队列有程序 就将等待队列队首程序放到执行队列队首
遇到end时 退出当前执行(不再进队尾)
#include <bits/stdc++.h>
using namespace std;
const int N = 1005;
bool lock;
deque<int> qr;//执行队列
queue<int> qb;//等待队列
vector<string> prg[N];
string s;
int t[N], p[N], var[26], lim;
void run(int i)
{
int rt = lim, v;
string cur;
while(rt > 0)
{
cur = prg[i][p[i]];
if(cur[2] == '=') // 赋值
{
rt -= t[0];
v = cur[4] - '0';
if(cur.size() == 6) v = v * 10 + cur[5] - '0';
var[cur[0] - 'a'] = v;
}
else if(cur[2] == 'i') //print
{
rt -= t[1];
printf("%d: %d\n", i, var[cur[6] - 'a']);
}
else if(cur[2] == 'c') //lock
{
rt -= t[2];
if(lock)
{
qb.push(i);
return;
}
else lock = true;
}
else if(cur[2] == 'l') //unlock
{
lock = false;
rt -= t[3];
if(!qb.empty())
{
v = qb.front();
qb.pop();
qr.push_front(v);
}
}
else return; //end
++p[i];
}
qr.push_back(i);
}
int main()
{
int cas, n;
scanf("%d", &cas);
while(cas--)
{
scanf("%d", &n);
for(int i = 0; i < 5; ++i)
scanf("%d", &t[i]);
scanf("%d", &lim);
for(int i = 1; i <= n; ++i)
{
prg[i].clear();
while(getline(cin, s))
{
if(s == "") continue;
prg[i].push_back(s);
if(prg[i].back() == "end") break;
}
qr.push_back(i);
}
memset(p, 0, sizeof(p));
memset(var, 0, sizeof(var));
while(!qr.empty())
{
int cur = qr.front();
qr.pop_front();
run(cur);
}
if(cas) puts("");
}
return 0;
}
| Concurrency Simulator |
Programs executed concurrently on a uniprocessor system appear to be executed at the same time, but in reality the single CPU alternates between the programs, executing some number of instructions from each program before switching to the next. You are to simulate the concurrent execution of up to ten programs on such a system and determine the output that they will produce.
The program that is currently being executed is said to be running, while all programs awaiting execution are said to be ready. A program consists of a sequence of no more than 25 statements, one per line, followed by an end statement. The statements available are listed below.
Each statement requires an integral number of time units to execute. The running program is permitted to continue executing instructions for a period of time called its quantum. When a program?s time quantum expires, another ready program will be selected to run. Any instruction currently being executed when the time quantum expires will be allowed to complete.
Programs are queued first-in-first-out for execution in a ready queue. The initial order of the ready queue corresponds to the original order of the programs in the input file. This order can change, however, as a result of the execution of lock and unlock statements.
The lock and unlock statements are used whenever a program wishes to claim mutually exclusive access to the variables it is manipulating. These statements always occur in pairs, bracketing one or more other statements. A lock will always precede an unlock, and these statements will never be nested. Once a program successfully executes a lock statement, no other program may successfully execute a lock statement until the locking program runs and executes the corresponding unlockstatement. Should a running program attempt to execute a lock while one is already in effect, this program will be placed at the end of the blocked queue. Programs blocked in this fashion lose any of their current time quantum remaining. When an unlock is executed, any program at the head of the blocked queue is moved to the head of the ready queue. The first statement this program will execute when it runs will be the lock statement that previously failed. Note that it is up to the programs involved to enforce the mutual exclusion protocol through correct usage of lock andunlock statements. (A renegade program with no lock/unlock pair could alter any variables it wished, despite the proper use of lock/unlock by the other programs.)
The input begins with a single positive integer on a line by itself indicating the number of the cases following, each of them as described below. This line is followed by a blank line, and there is also a blank line between two consecutive inputs.
The first line of the input file consists of seven integers separated by spaces. These integers specify (in order): the number of programs which follow, the unit execution times for each of the five statements (in the order given above), and the number of time units comprising the time quantum. The remainder of the input consists of the programs, which are correctly formed from statements according to the rules described above.
All program statements begin in the first column of a line. Blanks appearing in a statement should be ignored. Associated with each program is an identification number based upon its location in the input data (the first program has ID = 1, the second has ID = 2, etc.).
For each test case, the output must follow the description below. The outputs of two consecutive cases will be separated by a blank line.
Your output will contain of the output generated by the print statements as they occur during the simulation. When a print statement is executed, your program should display the program ID, a colon, a space, and the value of the selected variable. Output from separate print statements should appear on separate lines.
A sample input and correct output are shown below.
1 3 1 1 1 1 1 1 a = 4 print a lock b = 9 print b unlock print b end a = 3 print a lock b = 8 print b unlock print b end b = 5 a = 17 print a print b lock b = 21 print b unlock print b end
1: 3 2: 3 3: 17 3: 9 1: 9 1: 9 2: 8 2: 8 3: 21 3: 21
UVa 210 Concurrency Simulator(双端队列)
原文地址：http://blog.csdn.net/acvay/article/details/43054111
