磁盘调度算法c++

磁盘调度算法是操作系统中的一种重要算法，用于调度硬盘上的读写请求。常见的磁盘调度算法有FCFS、SSTF、SCAN、C-SCAN等。以下是一个简单的磁盘调度算法的C++代码示例，仅供参考：

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

// 定义存储磁盘请求的结构体
struct Request {
    int track; // 磁道号
    int time; // 到达时间
};

// FCFS磁盘调度算法
void FCFS(vector<Request>& req, int start) {
    int curr = start; // 当前磁道号
    int total = 0; // 总移动距离
    for (int i = 0; i < req.size(); i++) {
        total += abs(curr - req[i].track);
        curr = req[i].track;
    }
    cout << "FCFS: " << total << endl;
}

// SSTF磁盘调度算法
void SSTF(vector<Request>& req, int start) {
    int curr = start;
    int total = 0;
    while (!req.empty()) {
        int idx = 0, min_dist = INT_MAX;
        for (int i = 0; i < req.size(); i++) {
            int dist = abs(curr - req[i].track);
            if (dist < min_dist) {
                idx = i;
                min_dist = dist;
            }
        }
        total += min_dist;
        curr = req[idx].track;
        req.erase(req.begin() + idx);
    }
    cout << "SSTF: " << total << endl;
}

// SCAN磁盘调度算法
void SCAN(vector<Request>& req, int start, int end) {
    int curr = start;
    int total = 0;
    vector<Request> left, right;
    for (int i = 0; i < req.size(); i++) {
        if (req[i].track < start) left.push_back(req[i]);
        else if (req[i].track > end) right.push_back(req[i]);
        else continue;
    }
    sort(left.begin(), left.end(), [](Request& a, Request& b) { return a.track > b.track; });
    sort(right.begin(), right.end(), [](Request& a, Request& b) { return a.track < b.track; });
    for (int i = 0; i < left.size(); i++) {
        total += abs(curr - left[i].track);
        curr = left[i].track;
    }
    total += end - start;
    curr = end;
    for (int i = 0; i < right.size(); i++) {
        total += abs(curr - right[i].track);
        curr = right[i].track;
    }
    cout << "SCAN: " << total << endl;
}

// C-SCAN磁盘调度算法
void CSCAN(vector<Request>& req, int start, int end) {
    int curr = start;
    int total = 0;
    vector<Request> left, right;
    for (int i = 0; i < req.size(); i++) {
        if (req[i].track < start) left.push_back(req[i]);
        else if (req[i].track > end) right.push_back(req[i]);
        else continue;
    }
    sort(left.begin(), left.end(), [](Request& a, Request& b) { return a.track > b.track; });
    sort(right.begin(), right.end(), [](Request& a, Request& b) { return a.track < b.track; });
    for (int i = 0; i < left.size(); i++) {
        total += abs(curr - left[i].track);
        curr = left[i].track;
    }
    total += end - start;
    curr = end;
    for (int i = 0; i < right.size(); i++) {
        total += abs(curr - right[i].track);
        curr = right[i].track;
    }
    curr = start;
    for (int i = 0; i < left.size(); i++) {
        total += abs(curr - left[i].track);
        curr = left[i].track;
    }
    cout << "C-SCAN: " << total << endl;
}

int main() {
    vector<Request> req { {55, 0}, {58, 3}, {39, 8}, {18, 13}, {90, 17}, {160, 22}, {150, 28}, {38, 39} };
    FCFS(req, 50);
    SSTF(req, 50);
    SCAN(req, 50, 200);
    CSCAN(req, 50, 200);
    return 0;
}

以上代码实现了四种磁盘调度算法：FCFS、SSTF、SCAN、C-SCAN。其中，FCFS算法按照请求的先后顺序依次处理，SSTF算法每次选择离当前磁道号最近的请求，SCAN算法按照磁道号方向依次处理，C-SCAN算法则是在SCAN算法的基础上，将磁道号从尾部到头部再处理一遍。