A character in UTF8 can be from 1 to 4 bytes long, subjected to the following rules:
- For 1-byte character, the first bit is a 0, followed by its unicode code.
- For n-bytes character, the first n-bits are all one's, the n+1 bit is 0, followed by n-1 bytes with most significant 2 bits being 10.
This is how the UTF-8 encoding would work:
Char. number range | UTF-8 octet sequence
(hexadecimal) | (binary)
--------------------+---------------------------------------------
0000 0000-0000 007F | 0xxxxxxx
0000 0080-0000 07FF | 110xxxxx 10xxxxxx
0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
Given an array of integers representing the data, return whether it is a valid utf-8 encoding.
Note:
The input is an array of integers. Only the least significant 8 bits of each integer is used to store the data. This means each integer represents only 1 byte of data.
Example 1:
data = [197, 130, 1], which represents the octet sequence: 11000101 10000010 00000001. Return true. It is a valid utf-8 encoding for a 2-bytes character followed by a 1-byte character.
Example 2:
data = [235, 140, 4], which represented the octet sequence: 11101011 10001100 00000100. Return false. The first 3 bits are all one's and the 4th bit is 0 means it is a 3-bytes character. The next byte is a continuation byte which starts with 10 and that's correct. But the second continuation byte does not start with 10, so it is invalid.
class Solution(object):
#数 最开始有多少个零
def countNumOfOne(self,s):
res = 0
for i in s:
if i != '1':
break
res += 1
return res
#把字符串补全八位
def resize(self,s):
s = '0' * (8-len(s)) + s
return s
def validUtf8(self, data):
j = 1
i = self.resize(bin(data[0])[2:])
l = self.countNumOfOne(i) - 1
if len(data) == 1:
return l == -1
if l == -1:
l = 0
# print l
# print i,' ',l
while j < len(data):
i = self.resize(bin(data[j])[2:])
temp_len = self.countNumOfOne(i)
# print i,temp_len,l
#l>1,说明后面还应该有,所以如果当前字节不是一位的,就错了
if l >= 1:
if temp_len != 1:
return False
l -= 1
#如果l==0,说明之前的多位的已经结束了,如果当前还是一个1开头,那就错了
elif l == 0:
if temp_len == 1:
return False
l = temp_len - 1
if l == -1:
l = 0
else:
if temp_len != 0:
return False
else:
l = 0