Title: Generate a schedule for a round robin tournament in C#
For a description of teh algorithm, see University of Cambridge, NRICH: Tournament Scheduling.
Function GenerateRoundRobinOdd returns an array where results[i, j] gives the opponent of team i in round j of the round robin tournament. This function works only for an odd number of teams. The link above explains the method.
private const int BYE = -1;
// Return an array where results(i, j) gives
// the opponent of team i in round j.
// Note: num_teams must be odd.
private int [,] GenerateRoundRobinOdd(int num_teams)
int n2 = (int)((num_teams - 1) / 2);
int[,] results = new int[num_teams, num_teams];
// Initialize the list of teams.
int teams = new int[num_teams];
for (int i = 0; i < num_teams; i++) teams[i] = i;
// Start the rounds.
for (int round = 0; round < num_teams; round++)
for (int i = 0; i < n2; i++)
int team1 = teams[n2 - i];
int team2 = teams[n2 + i + 1];
results[team1, round] = team2;
results[team2, round] = team1;
// Set the team with the bye.
results[teams, round] = BYE;
// Rotate the array.
Helper function RotateArray rotates the items in the team array. The algorithm calls this routine after each round.
// Rotate the entries one position.
private void RotateArray(int teams)
int tmp = teams[teams.Length - 1];
Array.Copy(teams, 0, teams, 1, teams.Length - 1);
teams = tmp;
Function GenerateRoundRobinEven returns a similar array for an even number of teams. It calls GenerateRoundRobinOdd to make a schedule for a tournament with one fewer teams. It then expands the result array and replaces the byes with the additional team. See the link above for a more complete explanation.
private int[,] GenerateRoundRobinEven(int num_teams)
// Generate the result for one fewer teams.
int[,] results = GenerateRoundRobinOdd(num_teams - 1);
// Copy the results into a bigger array,
// replacing the byes with the extra team.
int[,] results2 = new int[num_teams, num_teams - 1];
for (int team = 0; team < num_teams - 1; team++)
for (int round = 0; round < num_teams - 1; round++)
if (results[team, round] == BYE)
// Change the bye to the new team.
results2[team, round] = num_teams - 1;
results2[num_teams - 1, round] = team;
results2[team, round] = results[team, round];
Function GenerateRoundRobin simply calls functions GenerateRoundRobinOdd and GenerateRoundRobinEven depending on whether the number of teams is odd or even.
private int[,] GenerateRoundRobin(int num_teams)
if (num_teams % 2 == 0)
Download the example to experiment with it and to see additional details.