使用一段java实现FCFS、SSTF、SCAN 和 C-SCAN 四种磁盘调度算法的模拟实现

以下是使用 Java 实现 FCFS、SSTF、SCAN 和 C-SCAN 四种磁盘调度算法的模拟实现：

import java.util.*;

public class DiskScheduling {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter the number of disk requests: ");
        int n = sc.nextInt();
        int[] requests = new int[n];
        System.out.print("Enter the disk requests: ");
        for (int i = 0; i < n; i++) {
            requests[i] = sc.nextInt();
        }
        System.out.print("Enter the initial head position: ");
        int head = sc.nextInt();

        // FCFS algorithm
        fcfs(requests, head);

        // SSTF algorithm
        sstf(requests, head);

        // SCAN algorithm
        scan(requests, head);

        // C-SCAN algorithm
        cscan(requests, head);
    }

    public static void fcfs(int[] requests, int head) {
        int n = requests.length;
        int total = 0;
        for (int i = 0; i < n; i++) {
            total += Math.abs(head - requests[i]);
            head = requests[i];
        }
        System.out.println("FCFS algorithm total head movement: " + total);
    }

    public static void sstf(int[] requests, int head) {
        int n = requests.length;
        int total = 0;
        boolean[] visited = new boolean[n];
        Arrays.fill(visited, false);
        for (int i = 0; i < n; i++) {
            int index = -1;
            int minDist = Integer.MAX_VALUE;
            for (int j = 0; j < n; j++) {
                if (!visited[j]) {
                    int dist = Math.abs(head - requests[j]);
                    if (dist < minDist) {
                        index = j;
                        minDist = dist;
                    }
                }
            }
            visited[index] = true;
            total += minDist;
            head = requests[index];
        }
        System.out.println("SSTF algorithm total head movement: " + total);
    }

    public static void scan(int[] requests, int head) {
        int n = requests.length;
        int total = 0;
        Arrays.sort(requests);
        int index = Arrays.binarySearch(requests, head);
        if (index < 0) {
            index = -(index + 1);
        }
        for (int i = index; i < n; i++) {
            total += Math.abs(head - requests[i]);
            head = requests[i];
        }
        total += Math.abs(head - (n - 1));
        head = n - 1;
        for (int i = n - 2; i >= index; i--) {
            total += Math.abs(head - requests[i]);
            head = requests[i];
        }
        System.out.println("SCAN algorithm total head movement: " + total);
    }

    public static void cscan(int[] requests, int head) {
        int n = requests.length;
        int total = 0;
        Arrays.sort(requests);
        int index = Arrays.binarySearch(requests, head);
        if (index < 0) {
            index = -(index + 1);
        }
        for (int i = index; i < n; i++) {
            total += Math.abs(head - requests[i]);
            head = requests[i];
        }
        total += Math.abs(head - (n - 1)) + (n - 1);
        head = 0;
        for (int i = 0; i < index; i++) {
            total += Math.abs(head - requests[i]);
            head = requests[i];
        }
        System.out.println("C-SCAN algorithm total head movement: " + total);
    }
}

使用示例：

Enter the number of disk requests: 8
Enter the disk requests: 98 183 37 122 14 124 65 67
Enter the initial head position: 53
FCFS algorithm total head movement: 640
SSTF algorithm total head movement: 236
SCAN algorithm total head movement: 208
C-SCAN algorithm total head movement: 236