dilemmap/main.js

const ALLC = function allwaysCooperate(foeHistory) {
    return true;
}

const ALLD = function allwaysDefect(foeHistory) {
    return false;
}

const RAND = function randomChoice(foeHistory) {
    if (Math.random() > 0.5) {
        return true;
    }
    return false;
}

const TFT = function titForThat(foeHistory) {
    if (foeHistory.length === 0) {
        return true;
    }
    return foeHistory[foeHistory.length - 1];
}

const STFT = function suspiciousTitForTat(foeHistory) {
    if (foeHistory.length === 0) {
        return false;
    }
    return foeHistory[foeHistory.length - 1];
}

const GRIM = function grimTrigger(foeHistory) {
    if (foeHistory.some(e => e === false)) {
        return false;
    }
    return true;
}

const MAJ = function majority(foeHistory) {
    let nbTrue = 0;
    let nbFalse = 0;

    for (const valeur of foeHistory) {
        if (valeur) {
            nbTrue++;
        } else {
            nbFalse++;
        }
    }
    if (nbTrue < nbFalse) {
        return false;
    }
    return true;
}

class Party {
    constructor(length, functions) {
        this.length = length;

        // if a list of active strategies is provided, use it,
        // otherwise fall back to all seven by default
        this.functions = (functions && functions.length > 0)
            ? functions
            : [ALLC, ALLD, RAND, TFT, STFT, GRIM, MAJ];

        this.grid = [];

        for (let i = 0; i < this.length; i++) {
            this.grid[i] = [];

            for (let j = 0; j < this.length; j++) {
                const index = Math.floor(Math.random() * this.functions.length);
                this.grid[i][j] = this.functions[index];
            }
        }
    }

    reset(functions) {
        // if a new list of active strategies is passed, update it;
        // otherwise keep the current selection
        if (functions && functions.length > 0) {
            this.functions = functions;
        }

        this.grid = [];
        for (let i = 0; i < this.length; i++) {
            this.grid[i] = [];

            for (let j = 0; j < this.length; j++) {
                const index = Math.floor(Math.random() * this.functions.length);
                this.grid[i][j] = this.functions[index];
            }
        }
    }

    step(T = 5, R = 3, P = 1, S = 0) {
        const nbRound = 50;

        let scores = [];

        for (let i = 0; i < this.length; i++) {
            scores[i] = [];
            for (let j = 0; j < this.length; j++) {
                scores[i][j] = 0;
            }
        }

        // computing scores
        for (let i = 0; i < this.length; i++) {
            for (let j = 0; j < this.length; j++) {
                for (let di = -1; di < 2; di++) {
                    for (let dj = -1; dj < 2; dj ++) {
                        if (di !== 0 || dj !== 0) {
                            const ni = (i + di + this.length) % this.length;
                            const nj = (j + dj + this.length) % this.length;

                            let playerHist = [];
                            let playerStrat = this.grid[i][j];

                            let foeHist = [];
                            let foeStrat = this.grid[ni][nj];

                            for (let k = 0; k < nbRound; k++) {
                                let playerMove = playerStrat(foeHist);
                                let foeMove = foeStrat(playerHist);

                                playerHist.push(playerMove);
                                foeHist.push(foeMove);

                                if (playerMove && foeMove) { // both shared
                                    scores[i][j] += R;
                                    scores[ni][nj] += R;
                                } else if (playerMove && !foeMove) { // player lose
                                    scores[i][j] += S;
                                    scores[ni][nj] += T;
                                } else if (!playerMove && foeMove) { // foe lose
                                    scores[i][j] += T;
                                    scores[ni][nj] += S;
                                } else { // both lose
                                    scores[i][j] += P;
                                    scores[ni][nj] += P;
                                }
                            }
                        }
                    }
                }
            }
        }

        let newGrid = [];

        for (let i = 0; i < this.length; i++) {
            newGrid[i] = [];
            for (let j = 0; j < this.length; j++) {
                newGrid[i][j] = 0;
            }
        }

        // changing strats
        for (let i = 0; i < this.length; i++) {
            for (let j = 0; j < this.length; j++) {
                let bestScore = scores[i][j];
                newGrid[i][j] = this.grid[i][j];
                for (let di = -1; di < 2; di++) {
                    for (let dj = -1; dj < 2; dj ++) {
                        if (di !== 0 || dj !== 0) {
                            const ni = (i + di + this.length) % this.length;
                            const nj = (j + dj + this.length) % this.length;

                            if (scores[ni][nj] > bestScore) { // someone has a better strategy
                                newGrid[i][j] = this.grid[ni][nj];
                                bestScore = scores[ni][nj];
                            }
                        }
                    }
                }
            }
        }

        this.grid = newGrid;
    }
}