weekday_to_number.js

var m = [
    'Monday',
    'Tuesday',
    'Wednesday',
    'Thursday',
    'Friday',
    'Saturday',
    'Sunday'
]
const N = [].concat(
    new Array(100).fill(0).map((_, i) => i),
    new Array(100).fill(0).map((_, i) => -i),
)
const D = Object.keys(m.reduce(
    (h, w) => {
        w.split('').map(c => h[c] = 1)
        return h
    }, {}))

const bfs = [
    (day, a, b, c, x, y, r) => r == (a * day.indexOf(x) + b * day.indexOf(y) + c) % 7,
    (day, a, b, c, x, y, r) => r == (a * day.indexOf(x) % b * day.indexOf(y) + c) % 7,
    (day, a, b, c, x, y, r) => r == ((a * day.indexOf(x) * day.indexOf(y) % b) + c) % 7,
    (day, a, b, c, x, y, r) => r == (((a * day.indexOf(x) + b) % day.indexOf(y)) + c) % 7,
    (day, a, b, c, x, y, r) => r == ((a * day.indexOf(x) + b) % day.indexOf(y)) % 7,
    (day, a, b, c, x, y, r) => r == (a * day.indexOf(x) * day.indexOf(y) + b) % 7,
    (day, a, b, c, x, y, r) => r == (a * day.indexOf(y) % b * day.length + c) % 7,
    (day, a, b, c, x, y, r) => r == ((a * day.indexOf(y) + b) % day.length) % 7,
    (day, a, b, c, x, y, r) => r == (a * day.length + b * day.indexOf(y) + c) % 7,
    (day, a, b, c, x, y, r) => r == (a * day.length % b * day.indexOf(y) + c) % 7,
    (day, a, b, c, x, y, r) => r == ((a * day.length * day.indexOf(y) % b) + c) % 7,
    (day, a, b, c, x, y, r) => r == (((a * day.length + b) % day.indexOf(y)) + c) % 7,
    (day, a, b, c, x, y, r) => r == (((a * day.length + b) % day.indexOf(y)) % c) % 7,
    (day, a, b, c, x, y, r) => r == ((a * day.length * day.indexOf(y) + b) % c) % 7
]

N.forEach(a =>
    N.forEach(b =>
        N.forEach(c =>
            D.forEach(x =>
                D.forEach(y => {
                    var oks = bfs.map(() => true)
                    for (var i = 0;i < m.length;i++) {
                        oks = bfs.map((bf, n) =>
                            oks[n] && bf(m[i], a, b, c, x, y, i)
                        )
                    }
                    oks.map((ok, i) => ok && console.log(bfs[i], a, b, c, x, y))
                })
            )
        )
    )
)