Package g0301_0400.s0393_utf_8_validation

Class Solution

  • public class Solution
extends Object
    393 - UTF-8 Validation.

    Medium

    Given an integer array data representing the data, return whether it is a valid UTF-8 encoding.

    A character in UTF8 can be from 1 to 4 bytes long, subjected to the following rules:

    1. For a 1-byte character, the first bit is a 0, followed by its Unicode code.
    2. For an n-bytes character, the first n bits are all one’s, the n + 1 bit is 0, followed by n - 1 bytes with the 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

    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:

    Input: data = [197,130,1]

    Output: true

    Explanation: data represents the octet sequence: 11000101 10000010 00000001. It is a valid utf-8 encoding for a 2-bytes character followed by a 1-byte character.

    Example 2:

    Input: data = [235,140,4]

    Output: false

    Explanation: data represented the octet sequence: 11101011 10001100 00000100. 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.

    Constraints:

    • 1 <= data.length <= 2 * 104
    • 0 <= data[i] <= 255

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • validUtf8

        public boolean validUtf8​(int[] data)