for seed = 1:100
    rng(seed, 'twister');      % seed

    % T = temptation--------5
    T = 5;
    % R = reward------------3
    R = 3;
    % P = punishment--------1
    P = 1;
    % S = sucker------------0
    S = 0;

    max = zeros(100,1);

    % A = (initial, defect, cooperate, score)
    rand_result = randi([0, 1], 20, 3);      % 0 == cooperate, 1 == defect
    agents = zeros(20,4);
    for agentNo = 1:20
        agents(agentNo,:) = [rand_result(agentNo,:), 0];
    end

    % game playing
    for generation = 1:100
        for agentNo = 1:20

            agent = agents(agentNo,:);

            for opponentNo = agentNo:20
                if opponentNo ~= agentNo

                    opponent = agents(opponentNo,:);

                    s_agent = agent(1);
                    s_opponent = opponent(1);

                    for game = 1:100

                        if s_agent == 0 && s_opponent == 0
                                agents(agentNo, 4) = agents(agentNo, 4) + R;
                                agents(opponentNo, 4) = agents(opponentNo, 4) + R;
                                s_agent = agent(3);
                                s_opponent = opponent(3);

                        elseif s_agent == 0 && s_opponent == 1
                                agents(agentNo, 4) = agents(agentNo, 4) + S;
                                agents(opponentNo, 4) = agents(opponentNo, 4) + T;
                                s_agent = agent(2);
                                s_opponent = opponent(3);

                        elseif s_agent == 1 && s_opponent == 0
                                agents(agentNo, 4) = agents(agentNo, 4) + T;
                                agents(opponentNo, 4) = agents(opponentNo, 4) + S;
                                s_agent = agent(3);
                                s_opponent = opponent(2);

                        elseif s_agent == 1 && s_opponent == 1
                                agents(agentNo, 4) = agents(agentNo, 4) + P;
                                agents(opponentNo, 4) = agents(opponentNo, 4) + P;
                                s_agent = agent(2);
                                s_opponent = opponent(2);

                        end
                    end
                end
            end
        end

        % sort agents by score
        agents = sortrows(agents,4,'descend');

        % record max of each generation
        max(generation) = agents(1,4)/(1900);

        % copy best 10 agents and clear scoreboard
        agents(1:10, 4) = 0;
        agents(11:20,:) = agents(1:10,:);

        % mutation
        for agentNo = 1:20
            for agentS = 1:3
                random_int = randi([1,100]);
                if random_int == 1
                    agents(agentNo,agentS) = ~agents(agentNo, agentS);
                end
            end
        end
    end
    hold on;
    xlabel('generation')
    ylabel('average-payoff')
    xlim([0 100])
    ylim([0 5])
    title('Student ID: 20129070')
    plot(max)
end