Hi, here’s your problem today. This problem was recently asked by Microsoft:

A UTF-8 character encoding is a variable width character encoding that can vary from 1 to 4 bytes depending on the character. The structure of the encoding is as follows:

1 byte:  0xxxxxxx
2 bytes: 110xxxxx 10xxxxxx
3 bytes: 1110xxxx 10xxxxxx 10xxxxxx
4 bytes: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx

For more information, you can read up on the Wikipedia Page.

Given a list of integers where each integer represents 1 byte, return whether or not the list of integers is a valid UTF-8 encoding.

BYTE_MASKS = [
    None,
    0b10000000,
    0b11100000,
    0b11110000,
    0b11111000,
]
BYTE_EQUAL = [
    None,
    0b00000000,
    0b11000000,
    0b11100000,
    0b11110000,
]

def utf8_validator(bytes):
  # Fill this in.

print utf8_validator([0b00000000])
# True
print utf8_validator([0b00000000, 10000000])
# False
print utf8_validator([0b11000000, 10000000])
# True