rendezvous with cassidoo #190 - Interview question of the week

superUgly.js

/**
 * From: https://buttondown.email/cassidoo/archive/to-understand-is-to-invent-jean-piaget/
 * @param {number} n Integer
 * @param {number[]} primes Sorted array of prime integers
 * @returns {number} Return the nth positive number whose all prime factors are in the array primes.
 * @example
 * $ superUgly(1, [2, 3, 5])
 * -> 1
 * 
 * $ superUgly(11, [2, 7, 13, 19])
 * -> 49
 */
function superUgly (n, primes) {
    const base = primes.length
    let quocient = n - 1
    let ugly = 1

    while (quocient > 0) {
        const remaining = (quocient - 1) % base
        const index = remaining
        const number = primes[index]
        
        quocient = Math.floor((quocient - 1) / base)
        ugly = ugly * number
    }
    
    return ugly
}