UTF-8 Validation LeetCode Solution

Here, We see UTF-8 Validation LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

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UTF-8 Validation LeetCode Solution

UTF-8 Validation LeetCode Solution

Problem Statement

Given an integer array data representing the data, return whether it is a valid UTF-8 encoding (i.e. it translates to a sequence of valid UTF-8 encoded characters).

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: Number of Bytes | UTF-8 Octet Sequence | (binary) ——————–+—————————————– 1 | 0xxxxxxx 2 | 110xxxxx 10xxxxxx 3 | 1110xxxx 10xxxxxx 10xxxxxx 4 | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx

x denotes a bit in the binary form of a byte that may be either 0 or 1.

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.

UTF-8 Validation LeetCode Solution C++

class Solution {
public:
    bool validUtf8(vector<int>& data) {
        int remaining = 0;
        for (auto& x : data) {
            if (remaining == 0) {
                if ((x >> 5) == 0b110) {
                    remaining = 1;
                } else if ((x >> 4) == 0b1110) {
                     remaining = 2;
                } else if ((x >> 3) == 0b11110) {
                    remaining = 3;
                } else if ((x >> 7) != 0) {
                    return false;
                }
            } else {
                if ((x >> 6) != 0b10) return false;
                else remaining--;
            }
        }
        return remaining == 0;
    }
};Code language: PHP (php)

UTF-8 Validation LeetCode Solution Java

class Solution {
    public boolean validUtf8(int[] data) {
        if(data==null || data.length==0) return false;
        boolean isValid = true;
        for(int i=0;i<data.length;i++) {
            if(data[i]>255) return false;
            int numberOfBytes = 0;
            if((data[i] & 128) == 0) {
                numberOfBytes = 1;
            } else if((data[i] & 224) == 192) {
                numberOfBytes = 2;
            } else if((data[i] & 240) == 224) {
                numberOfBytes = 3;
            } else if((data[i] & 248) == 240) {
                numberOfBytes = 4;
            } else {
                return false;
            }
            for(int j=1;j<numberOfBytes;j++) {
                if(i+j>=data.length) return false;
                if((data[i+j] & 192) != 128) return false;
            }
            i=i+numberOfBytes-1;
        }
        return isValid;
    }
}Code language: PHP (php)

UTF-8 Validation LeetCode Solution JavaScript

var validUtf8 = function(data) {
    let binary = data.map((i)=>{
        let b = "00000000" + i.toString(2);
        return b.substring(b.length - 8);
    })
    let current = 0;
    for (let i=0;i<binary.length;i++) {
        let bytes = binary[i].indexOf('0');
        if (current==0) {
            if (bytes==0) continue;
            if (bytes > 4 || bytes < 2) return false;
            current = bytes;
        } else {
            if (bytes != 1) return false
        }
        current--;
    }
    return current==0;
};Code language: JavaScript (javascript)

UTF-8 Validation Solution Python

class Solution(object):
    def validUtf8(self, data):
        n = len(data)
        i = 0
        while i < n:
            valid_encoding = False
            if self.one_byte_encoding(data[i]):
                i += 1
                valid_encoding = True
            for byte_len in range(2, 4 + 1):
                if self.byte_encoding(byte_len, data, i):
                    i += byte_len
                    valid_encoding = True
                    break
            if not valid_encoding:
                return False
        return True
    def one_byte_encoding(self, number):
        if number & 1 << 7 == 0:
            return True
        return False
    def byte_encoding(self, byte_len, data, i):
        if i + byte_len > len(data):
            return False
        first_byte = data[i]
        for j in range(byte_len):
            if first_byte & 1<<(7-j) == 0:
                return False
        if first_byte & 1 << 7 - byte_len != 0:
            return False
        for j in range(i+1, i + 1 + (byte_len - 1)):
            if data[j] & 1<<7 == 0:
                return False
            if data[j] & 1<< 6 != 0:
                return False
        return True
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