// https://forum.arduino.cc/t/bowling-league-lane-assignment-problem/1005860

template <size_t N> void roundRobinEven(size_t (&rounds)[N][(N + 1) / 2][2]) {
  for (size_t r = 0; r < N; r++) {
    rounds[r][0][0] = r;
    rounds[r][0][1] = N;
    for (size_t i = 1; i < (N + 1) / 2; i++) {
      rounds[r][i][0] = (r + i) % N;
      rounds[r][i][1] = (r + N - i) % N;
    }
  }
}

template <size_t N> void printSchedule(size_t (&rounds)[N][(N + 1) / 2][2]) {
  char buffer[20];

  for (size_t r = 0; r < N; r++) {
    sprintf(buffer, "Round %i: ", r);
    Serial.print(buffer);
    for (size_t i = 0; i < (N + 1) / 2; i++) {
      sprintf(buffer, "(%i, %i) ", rounds[r][i][0], rounds[r][i][1]);
      Serial.print(buffer);
    }
    Serial.println();
  }
}


void setup() {
  Serial.begin(9600);

  size_t const teams = 36;
  size_t rounds[teams - 1][teams / 2][2];
  roundRobinEven(rounds);
  printSchedule(rounds);
}

void loop() {}