View Compilation Error

0_0_22258392_26455.cpp:40:14: error: 'string' has not been declared
  void insert(string s, int v) {
              ^
0_0_22258392_26455.cpp: In member function 'void Trie::insert(int, int)':
0_0_22258392_26455.cpp:41:20: error: request for member 'length' in 's', which is of non-class type 'int'
   int u = 0, n = s.length();
                    ^
0_0_22258392_26455.cpp:43:19: error: invalid types 'int[int]' for array subscript
    int c = idx(s[i]);
                   ^