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Java Solution for LeetCode algorithm problems, continually updating
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`