LeetCode 393: UTF-8 Validation Solution

Master LeetCode problem 393 (UTF-8 Validation), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

393. UTF-8 Validation

Medium

Array Bit Manipulation

Problem Explanation

Explanation:

To validate if the given data is a valid UTF-8 encoding, we need to check if it follows the given rules for UTF-8 encoding. We iterate over the given data array, check each byte to determine the number of bytes in the character it represents, and verify if the subsequent bytes are continuation bytes (start with "10"). If all bytes follow the rules, we return true; otherwise, we return false.

Detailed steps:

Iterate over the data array.
Determine the number of bytes in the current character based on the first few bits.
Check if the subsequent bytes are continuation bytes.
Repeat the process for each character.
Return true if all characters are valid UTF-8 encoded, false otherwise.

Time complexity: O(n), where n is the length of the data array. Space complexity: O(1) as we use constant extra space.

Solution Code

class Solution {
    public boolean validUtf8(int[] data) {
        int count = 0;
        for (int d : data) {
            if (count == 0) {
                if ((d >> 5) == 0b110) count = 1;
                else if ((d >> 4) == 0b1110) count = 2;
                else if ((d >> 3) == 0b11110) count = 3;
                else if ((d >> 7) == 0b1) return false;
            } else {
                if ((d >> 6) != 0b10) return false;
                count--;
            }
        }
        return count == 0;
    }
}

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