solution.c

// The solution is simple, just count the number of plants between two seats and multiply each of them.
// Tidak layak dikategorikan hard wkwk

const unsigned long mod = 1000000007;

int numberOfWays(char* corridor) {
  unsigned long count = 1;

  unsigned char seats = 0;
  unsigned long plants = 0;

  // Iterate through each character of the corridor string.
  while (*corridor != 0) {
    // Repeat until it finds 2 seats.
    if (seats < 2) {
      if (*corridor == 'S') ++seats;
    } else {
      // If 2 seats are found, check the next character.
      switch (*corridor) {
        case 'S':
          // If it is a seat, calculate the total count by multiplying it
          // with the number of plants + 1.
          if (plants > 0) count = (count * ++plants) % mod;

          // Reset the plants and seats counting.
          plants = 0;
          seats = 1;
          break;

        case 'P':
          // Count each next consecutive plant.
          ++plants;
          break;
      }
    }
    ++corridor;
  }

  // If the previous seats counting is not 2
  // then the total counting does not matter.
  if (seats != 2) return 0;

  return count;
}