_393.java

package com.fishercoder.solutions;

public class _393 {

    public static class Solution1 {
        /**
         * credit: https://discuss.leetcode.com/topic/58338/bit-manipulation-java-6ms/4
         */
        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) == 1) {
                        return false;
                    }
                } else {
                    if ((d >> 6) != 0b10) {
                        return false;
                    } else {
                        count--;
                    }
                }
            }
            return count == 0;
        }
    }

}