请帮我用c语言依次实现操作系统中磁盘调度算法FCFS算法和SSTF算法和SCAN算法和CSCAN算法。

以下是C语言实现FCFS、SSTF、SCAN、CSCAN四种磁盘调度算法的代码：

1. FCFS算法

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    int n, i, j, head, sum = 0;
    printf("请输入磁盘请求数量：");
    scanf("%d", &n);
    int a[n];
    printf("请输入磁盘请求序列：");
    for(i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
    }
    printf("请输入磁头初始位置：");
    scanf("%d", &head);
    for(i = 0; i < n; i++)
    {
        sum += abs(head - a[i]);
        head = a[i];
    }
    printf("磁头移动距离为：%d\n", sum);
    return 0;
}

2. SSTF算法

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    int n, i, j, head, sum = 0, min, index;
    printf("请输入磁盘请求数量：");
    scanf("%d", &n);
    int a[n], b[n];
    printf("请输入磁盘请求序列：");
    for(i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
        b[i] = 0;
    }
    printf("请输入磁头初始位置：");
    scanf("%d", &head);
    for(i = 0; i < n; i++)
    {
        min = 1000000;
        for(j = 0; j < n; j++)
        {
            if(b[j] == 0 && abs(head - a[j]) < min)
            {
                min = abs(head - a[j]);
                index = j;
            }
        }
        b[index] = 1;
        sum += min;
        head = a[index];
    }
    printf("磁头移动距离为：%d\n", sum);
    return 0;
}

3. SCAN算法

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    int n, i, j, head, sum = 0, min, index, flag = 0;
    printf("请输入磁盘请求数量：");
    scanf("%d", &n);
    int a[n], b[n];
    printf("请输入磁盘请求序列：");
    for(i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
        b[i] = 0;
    }
    printf("请输入磁头初始位置：");
    scanf("%d", &head);
    for(i = 0; i < n; i++)
    {
        min = 1000000;
        for(j = 0; j < n; j++)
        {
            if(b[j] == 0 && abs(head - a[j]) < min)
            {
                if(flag == 0 && a[j] >= head)
                {
                    min = abs(head - a[j]);
                    index = j;
                }
                else if(flag == 1 && a[j] <= head)
                {
                    min = abs(head - a[j]);
                    index = j;
                }
                else if(flag == 0 && a[j] < head)
                {
                    min = abs(head - a[j]);
                    index = j;
                }
                else if(flag == 1 && a[j] > head)
                {
                    min = abs(head - a[j]);
                    index = j;
                }
            }
        }
        b[index] = 1;
        sum += min;
        head = a[index];
        if(flag == 0 && head == 0)
        {
            flag = 1;
        }
        else if(flag == 1 && head == 199)
        {
            flag = 0;
        }
    }
    printf("磁头移动距离为：%d\n", sum);
    return 0;
}

4. CSCAN算法

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    int n, i, j, head, sum = 0, min, index, flag = 0;
    printf("请输入磁盘请求数量：");
    scanf("%d", &n);
    int a[n], b[n];
    printf("请输入磁盘请求序列：");
    for(i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
        b[i] = 0;
    }
    printf("请输入磁头初始位置：");
    scanf("%d", &head);
    for(i = 0; i < n; i++)
    {
        min = 1000000;
        for(j = 0; j < n; j++)
        {
            if(b[j] == 0 && abs(head - a[j]) < min)
            {
                if(flag == 0 && a[j] >= head)
                {
                    min = abs(head - a[j]);
                    index = j;
                }
                else if(flag == 1 && a[j] <= head)
                {
                    min = abs(head - a[j]);
                    index = j;
                }
            }
        }
        b[index] = 1;
        sum += min;
        head = a[index];
        if(flag == 0 && head == 199)
        {
            flag = 1;
            sum += 199;
            head = 0;
        }
        else if(flag == 1 && head == 0)
        {
            flag = 0;
            sum += 199;
            head = 199;
        }
    }
    printf("磁头移动距离为：%d\n", sum);
    return 0;
}