393. UTF-8 Validation

The idea is count bytes first and validate the following bytes.

1:  class Solution {  
2:  public:  
3:    bool validUtf8(vector<int>& data) {  
4:      int c = 0;  
5:      for (int d : data) {  
6:        if (c == 0) {  
7:          if ((d >> 7) == 0) c = 0;  
8:          else if ((d >> 5) == 0b110) c = 1;  
9:          else if ((d >> 4) == 0b1110) c = 2;  
10:          else if ((d >> 3) == 0b11110) c = 3;  
11:          else return false;  
12:        } else {  
13:          if ((d >> 6) != 0b10) return false;  
14:          c--;  
15:        }  
16:      }  
17:      return c == 0;  
18:    }  
19:  };