393.cpp

class Solution {
  // Runtime: 16 ms, faster than 79.20% of C++ online submissions for UTF-8
  // Validation. Memory Usage: 9.5 MB, less than 59.65% of C++ online
  // submissions for UTF-8 Validation.
public:
  bool validUtf8(vector<int> &data) {
    int status = 0;
    for (auto val : data) {
      auto d = val & 0xff;
      if (status) {
        if (not((d >> 6) == 0b10))
          return false;
        --status;
      } else {
        if ((d >> 7) == 0)
          ;
        else if ((d >> 5) == 0b110)
          status += 1;
        else if ((d >> 4) == 0b1110)
          status += 2;
        else if ((d >> 3) == 0b11110)
          status += 3;
        else
          return false;
      }
    }
    return status == 0;
  }
};