mathball/lib/frugal/index.js

A JavaScript library for Competitive Programming

'use strict';

/*
    Frugal Numbers tester
    function name: isFrugal()
*/

var validate = require('../validation/positive-integer');

function genPrimeList(inp) {

    var list = [];
    var count = 0,
        temp = inp;

    //testing for all multiples of 2
    while (temp % 2 === 0) {
        count++;
        temp = temp / 2;
    }

    if (count > 0) {
        list.push({ num: 2, occurance: count });
    }

    //for the remaining odd numbers. Note that prime numbers will remove their non-prime multiples BEFORE any
    //non- prime number can appear
    for (var i = 3; i < temp / 2; i += 2) {
        count = 0;
        while (inp % i === 0) {
            count++;
            inp = inp / i;
        }
        if (count > 0) {
            list.push({ num: i, occurance: count });
        }
    }
    return list;
}

exports.check = function (inp) {
    validate(inp, 'isFrugal');

    var primeFactorisation = genPrimeList(inp);
    var factorsLength = 0;
    var inpLength = inp.toString().length;

    for (var i = 0; i < primeFactorisation.length; i++) {

        factorsLength += primeFactorisation[i].num.toString().length;

        if (primeFactorisation[i].occurance > 1) {
            factorsLength += primeFactorisation[i].occurance.toString().length;
        }
    }

    return inpLength - factorsLength > 0 ? true : false;
};