anybody, please help me in figuring out the bitmasking used in candles counting problem on hackerrank (inclusion-exclusion principle approach) problem I am not able to clearly get what's being written in the editorial code. I know inclusion-exclusion principle but I am not able to clearly visualize the code thanks in advance.

int res = 0;
  for(int mask = 0; mask < (1 << K); mask ++){
    memset(ft, 0, sizeof ft);
    int tmp = 0;
    for(int i = 0; i < N; i++){
      if((mask >> (C[i] - 1)) & 1){
        dp[i] = 1 + query(H[i] - 1);
        madd(tmp, dp[i]);
        update(H[i], dp[i]);
      }
    }
    if(__builtin_popcount(mask) % 2 == K % 2){
      madd(res, tmp);
    } else {
      madd(res, mod - tmp);
    }
  }
  assertrange(res, 0, mod - 1);
  printf("%d\n", res);