#磁盘调度
n=int(input("请输入进程数："))

zhizhen=int(input("请输入指针初始位置："))
yemian=[]
yemian1=[]
yemian2=[]
yemian41=[]
def cunfang():#数据的存放
    for i in range(n):
        jincheng=int(input("请输入第%d进程所在位置"%(i+1)))
        yemian.append([jincheng,0])
        yemian41.append([0,0])
    print("您输入的界面信息为:")
    print(yemian)
def first():
    global zhizhen
    zhizhen1=zhizhen
    yidong=0
    yemian1=yemian[:]
    for i in range(n):
        yemian1[i][1]=abs(float(zhizhen1)-float(yemian1[i][0]))
        yidong=yidong+yemian[i][1]
        zhizhen1=yemian1[i][0]
    print("所得fcfs磁盘调度结果：")
    print(yemian1)
    yidong=float(yidong/n)
    print("平均寻道长度为：%0.1f"%(yidong))

def zhen():#排序等简单处理
    global zhizhen
    global zhi
    zhi=0
    yidong=0
    zhizhen1=zhizhen
    yemian2=yemian3[:]
    global qian
    qian=[]
    global hou
    hou=[]
    global right
    right=0
    for i in range(n):
        if(zhizhen1<=yemian2[i][0]):#问题：如果指针初始位置恰好在某一进程位置，会怎样？
            yidong=yemian2[i][0]
            zhi=i
            break
    if (yidong == zhizhen1):
        if (abs(yidong - yemian2[zhi - 1][0]) < abs(yidong - yemian2[zhi + 1][0])):
            zhi=zhi
            right=1
        else:
            zhi=zhi-1
    else:

        if(abs(zhizhen1 - yemian2[zhi - 1][0]) < abs(zhizhen1 - yemian2[zhi][0])):
            right=1
        else:
            right=0
        zhi = zhi - 1
    qian=yemian2[0:zhi+1]
    hou=yemian2[zhi+1:]


def sstf():
    global yemian41
    yemian4=yemian41[:]
    global zhizhen
    zhizhen1=zhizhen
    global right
    global zhi
    global qian
    qian1=qian[:]
    global hou
    ppp=0
    global n
    hou1=hou[:]
    qqq=0
    zhi1=zhi

    if(right==1):
        while(zhi1>=0):
            yemian4[ppp][0]=qian1[zhi1][0]
            yemian4[ppp][1]=zhizhen1-qian1[zhi1][0]
            zhizhen1=yemian4[ppp][0]
            zhi1=zhi1-1
            ppp=ppp+1
        ppp=0
        zhi1=zhi+1
        while(zhi1<n):

            yemian4[zhi1][0]=hou1[ppp][0]
            yemian4[zhi1][1]=hou1[ppp][0]-zhizhen1
            zhizhen1=hou1[ppp][0]
            zhi1=zhi1+1
            ppp=ppp+1

    else:
        zhi1=zhi
        ppp=0
        zhizhen1=zhizhen
        while(ppp<n-zhi1-1):
            yemian4[ppp][0]=hou1[ppp][0]
            yemian4[ppp][1]=hou1[ppp][0]-zhizhen1
            zhizhen1 = hou1[ppp][0]
            ppp=ppp+1

        while(zhi1>=0):
            yemian4[ppp][1]=zhizhen1-qian1[zhi1][0]
            yemian4[ppp][0]=qian[zhi1][0]
            zhi1=zhi1-1
            zhizhen1=qian[zhi1][0]
            ppp=ppp+1
    print("所得sstf磁盘调度结果：")
    print(yemian4)
    for i in range(n):
        qqq=qqq+yemian4[i][1]
    qqq=float(qqq/n)
    print("平均寻道长度为：%0.1f"%(qqq))




def scan():
    global  zhizhen
    zhizhen1=zhizhen
    global yemian3
    yemian2=yemian3[:]
    zhi3=0
    ppp=0
    for i in range(n):
        if(zhizhen1<=yemian2[i][0]):#问题：如果指针初始位置恰好在某一进程位置，会怎样？

            zhi3=i
            break
    zhi4=zhi3
    global yemian41
    while(zhi4<n):
        yemian41[ppp][0]=yemian2[zhi4][0]
        yemian41[ppp][1]=yemian2[zhi4][0]-zhizhen1
        zhizhen1=yemian2[zhi4][0]
        ppp=ppp+1
        zhi4=zhi4+1
    zhi4=zhi3-1
    while(zhi4>=0):
        yemian41[ppp][0]=yemian2[zhi4][0]
        yemian41[ppp][1] = zhizhen1-yemian2[zhi4][0]
        zhizhen1 = yemian2[zhi4][0]
        ppp = ppp + 1
        zhi4=zhi4-1
    qqq=0
    print("所得scan磁盘调度结果：")
    print(yemian41)
    for i in range(n):
        qqq=qqq+yemian41[i][1]
    qqq=float(qqq/n)
    print("平均寻道长度为：%0.1f"%(qqq))




def cscan():
    global  zhizhen
    zhizhen1=zhizhen
    global yemian3
    yemian2=yemian3[:]
    zhi3=0
    ppp=0
    qqq=0
    for i in range(n):
        if(zhizhen1<=yemian2[i][0]):#问题：如果指针初始位置恰好在某一进程位置，会怎样？

            zhi3=i
            break
    zhi4=zhi3
    global yemian41
    while(zhi4<n):
        yemian41[ppp][0]=yemian2[zhi4][0]
        yemian41[ppp][1]=yemian2[zhi4][0]-zhizhen1
        zhizhen1=yemian2[zhi4][0]
        ppp=ppp+1
        zhi4=zhi4+1
    zhi4 = zhi3
    while(qqq<zhi4):
        yemian41[ppp][0]=yemian2[qqq][0]
        yemian41[ppp][1]=abs(zhizhen1-yemian2[qqq][0])
        zhizhen1=yemian2[qqq][0]
        ppp=ppp+1
        qqq=qqq+1
    print("所得cscan磁盘调度结果：")
    print(yemian41)
    qqq=0
    for i in range(n):
        qqq = qqq + yemian41[i][1]
    qqq = float(qqq / n)
    print("平均寻道长度为：%0.1f" % (qqq))



if __name__ == '__main__':
    cunfang()
    yemian3 = yemian[:]
    yemian3.sort(key=lambda x: x[0], )
    print("进行简易排序：")
    print(yemian3)
    sss=0
    zhen()
    while(sss==0):
        print("请输入1，2，3，4选择FCFS。SSTF.SCAN.CSCAN等算法，其余终止程序(输入):")
        rrr=int(input())
        if(rrr==1):
            first()
        elif(rrr==2):
            sstf()
        elif(rrr==3):
            scan()
        elif(rrr==4):
            cscan()
        else:
            print("运行结束！")
            sss=1