View Compilation Error

0_0_17597657_21548.c: In function 'main':
0_0_17597657_21548.c:20:2: error: expected expression before '/' token
  //freopen("in.txt", "r", stdin);
  ^
0_0_17597657_21548.c:46:1: error: expected expression before '/' token
 //  sort(level, level + n, cmp);
 ^
0_0_17597657_21548.c:48:1: error: expected expression before '/' token
 //  for (int i = 0; i < n; i++)
 ^