Illustration of tentative RedLink lucky draw algorithm

redlink-join.ts

export let M = 0
export let F = 0
export type gender = 'm' | 'f'

export function add(gender: gender) {
    switch (gender) {
        case 'm':
            return M++;
        case 'f':
            return F++;
        default:
            throw new Error('unknown gender:' + gender)
    }
}

export function join(gender: gender) {
    if (M === F
        || (M > F && gender === 'f')
        || (F > M && gender === 'm')
    ) {
        return add(gender);
    }
    if (M * 2 === F || F * 2 === M) {
        return;
    }
    let prob = (gender === 'f' ? M : F) / (M + F);
    if (Math.random() < prob) {
        return add(gender)
    }
}

export function report(msg) {
    let R = F / M;
    if (R < 1) {
        R = M / F
    }
    R = Math.round(R * 100) / 100;
    console.log({F, M, R}, msg || '')
}

export function itr(gender: gender) {
    let res = join(gender);
    let msg = (res === undefined ? 'rejected' : 'accepted') + ' ' + gender;
    report(msg);
}

export function determine(f: number, m: number) {
    F = 0;
    M = 0;
    if (f === m) {
        F = f;
        M = m;
        return 'all accepted';
    }
    if (f > m) {
        F = M = m;
        f -= m;
        m = 0;
    }
    if (m > f) {
        F = M = f;
        m -= f;
        f = 0;
    }
    for (let i = 0; i < f; i++) {
        join('f')
    }
    for (let i = 0; i < m; i++) {
        join('m')
    }
}

export function main_sample_case() {
    let f = 50;
    let m = 100;
    determine(f, m);
    report('all done');
}

export function main_n(N?: number) {
    for (let n = 1; !N || n < N; n++) {
        let f = 0;
        let m = 0;
        for (let i = 0; i < n; i++) {
            let gen: gender = Math.random() < 1 / 3 ? 'f' : 'm';
            if (gen === 'f') {
                f++
            } else {
                m++
            }
        }
        determine(f, m);
        report({n, f, m})
    }
}

main_n();