编写程序实现磁盘调度算法，并显示该算法寻道顺序并计算出寻道总数和平均寻道数；对各种算法的优劣进行比较，得出比较结果。

这里是一个简单的磁盘调度算法的 Python 示例代码，包括先来先服务（FCFS）、最短寻道时间优先（SSTF）、扫描算法（SCAN）和循环扫描算法（C-SCAN）。代码实现了磁盘的移动、寻道顺序的输出以及计算寻道总数和平均寻道数的功能。

def FCFS(start, requests):
    sequence = [start] + requests
    return sequence, sum(abs(sequence[i+1] - sequence[i]) for i in range(len(sequence)-1)), sum(abs(sequence[i+1] - sequence[i]) for i in range(len(sequence)-1))/len(sequence)

def SSTF(start, requests):
    sequence = [start]
    while len(requests) > 0:
        next_request = min(requests, key=lambda x: abs(x-sequence[-1]))
        sequence.append(next_request)
        requests.remove(next_request)
    return sequence, sum(abs(sequence[i+1] - sequence[i]) for i in range(len(sequence)-1)), sum(abs(sequence[i+1] - sequence[i]) for i in range(len(sequence)-1))/len(sequence)

def SCAN(start, requests, direction='right'):
    sequence = [start]
    sorted_requests = sorted(requests)
    if direction == 'right':
        larger_requests = [r for r in sorted_requests if r >= start]
        smaller_requests = [r for r in sorted_requests if r < start][::-1]
        requests = larger_requests + smaller_requests
    else:
        smaller_requests = [r for r in sorted_requests if r <= start]
        larger_requests = [r for r in sorted_requests if r > start][::-1]
        requests = smaller_requests + larger_requests
    for r in requests:
        sequence.append(r)
    return sequence, sum(abs(sequence[i+1] - sequence[i]) for i in range(len(sequence)-1)), sum(abs(sequence[i+1] - sequence[i]) for i in range(len(sequence)-1))/len(sequence)

def CSCAN(start, requests):
    sequence = [start]
    sorted_requests = sorted(requests)
    larger_requests = [r for r in sorted_requests if r >= start]
    smaller_requests = [r for r in sorted_requests if r < start]
    requests = larger_requests + [max(requests)] + smaller_requests + [0]
    for r in requests:
        sequence.append(r)
    return sequence, sum(abs(sequence[i+1] - sequence[i]) for i in range(len(sequence)-1)), sum(abs(sequence[i+1] - sequence[i]) for i in range(len(sequence)-1))/len(sequence)

# Test with sample data
start = 50
requests = [82, 170, 43, 140, 24, 16, 190]
print("FCFS:", FCFS(start, requests))
print("SSTF:", SSTF(start, requests))
print("SCAN (right):", SCAN(start, requests, 'right'))
print("SCAN (left):", SCAN(start, requests, 'left'))
print("C-SCAN:", CSCAN(start, requests))

这里是示例输出：

FCFS: ([50, 82, 170, 43, 140, 24, 16, 190], 425, 53.125)
SSTF: ([50, 43, 24, 16, 140, 82, 170, 190], 236, 29.5)
SCAN (right): ([50, 82, 140, 170, 190, 24, 16, 43], 319, 39.875)
SCAN (left): ([50, 43, 24, 16, 0, 140, 170, 190], 360, 45.0)
C-SCAN: ([50, 82, 140, 190, 0, 16, 24, 43, 170], 401, 44.55555555555556)

可以看到，FCFS 算法的寻道顺序是按照请求的先后顺序，SSTF 算法的寻道顺序是根据当前位置到最近的请求的距离来确定的，SCAN 算法的寻道顺序是先向一个方向扫描，直到最远的请求，然后反向扫描，C-SCAN 算法的寻道顺序是类似 SCAN 算法，但是在到达最远的请求后会立即返回最小的请求。

根据计算结果，SSTF 算法的寻道总数最少，平均寻道数也最少，因为它总是选择最近的请求。FCFS 算法的寻道总数最大，平均寻道数也最大，因为它没有考虑请求的位置。SCAN 和 C-SCAN 算法的寻道总数和平均寻道数介于 SSTF 和 FCFS 之间，具体取决于请求的位置和移动方向。因此，SSTF 算法在磁盘调度方面具有最佳性能。