作业多得离谱，连老师自己都承认有 80% 的学生每天的作业是写不完的
首考假放完后要连上九天学，真是身心俱疲
刚刚信息课学的：
f=open("position.txt","r")
x=[0]
y=[0]
for line in f.readlines():
a=int(line.strip().split(",")[0])
b=int(line.strip().split(",")[1])
x.append(a)
y.append(b)
f.close()
print(x,y)
#求两点之间的距离函数
def juli(x1,x2,y1,y2):
s=((x2-x1)**2+(y2-y1)**2)**0.5
return s
long=0
for i in range(1,len(x)):
long=long+juli(x[i-1],x[i],y[i-1],y[i])
print(long)
max1=juli(x[-1],x[-2],y[-1],y[-2])
ansi=0
for i in range(1,len(x)-1):
d1=juli(x[i-1],x[i],y[i-1],y[i])
d2=juli(x[i],x[i+1],y[i],y[i+1])
d3=juli(x[i-1],x[i+1],y[i-1],y[i+1])
dx=d1+d2-d3
if dx>max1:
max1=dx
ansi=i
print(max1,ansi)
print("最短距离",long-max1)