题解 | #判断两个IP是否属于同一子网#

#判断IP地址是否有效
def isOK(s):
    for i in range(len(s)):
        if s[i] > 255 or s[i]<0:
            return False
    return True
# 判断掩码是否正确
def isPr(s):
    numob = []
    for i in s:
        i = bin(int(i))
        i = i[2:]
        numob.append(i.zfill(8))
    whole_mask = "".join(numob)
    if whole_mask.rfind("1")+1 == whole_mask.find("0"):
        return True
    return False

while True:
    try:
        s = list(map(int, input().split('.')))
        m1 = list(map(int, input().split('.')))
        m2 = list(map(int, input().split('.')))

        if isOK(s) == False or isOK(m1) == False or isOK(m2) == False or isPr(s)==False:
            print(1)
        elif s[0]&m1[0]==s[0]&m2[0] and s[1]&m1[1]==s[1]&m2[1] and s[2]&m1[2]==s[2]&m2[2] and s[3]&m1[3]==s[3]&m2[3]:
            print(0)
        else:
            print(2)
    except:
        break