题解 | 合法IP
def is_ip(s):
if s.count('.') != 3:
return 0
else:
ls = s.split('.')
for i in ls:
if i.isdigit():
if 0<int(i)<=255 and i[0] != '0':
continue
elif i == '0':
continue
else:
return 0
else:
return 0
return 1
while True:
try:
s = input()
if is_ip(s):
print('YES')
else:
print('NO')
except:
break