charge_time_calculation.js

// Description:
//     Task
// To charge your mobile phone battery, do you know how much time it takes from 0% to 100%? It depends on your cell phone battery capacity and the power of the charger. A rough calculation method is:
//
//     0% --> 85%  (fast charge)
// (battery capacity(mAh) * 85%) / power of the charger(mA)
//
// 85% --> 95% (decreasing charge)
// (battery capacity(mAh) * 10%) / (power of the charger(mA) * 50%)
//
// 95% --> 100% (trickle charge)
// (battery capacity(mAh) * 5%) / (power of the charger(mA) * 20%)
// For example: Your battery capacity is 1000 mAh and you use a charger 500 mA, to charge your mobile phone battery from 0% to 100% needs time:
//
//     0% --> 85%  (fast charge) 1.7 (hour)
//
// 85% --> 95% (decreasing charge) 0.4 (hour)
//
// 95% --> 100% (trickle charge) 0.5 (hour)
//
// total times = 1.7 + 0.4 + 0.5 = 2.6 (hour)
// Complete function calculateTime that accepts two arguments battery and charger, return how many hours can charge the battery from 0% to 100%. The result should be a number, round to 2 decimal places (In Haskell, no need to round it).

// SOLUTION:

function calculateTime(battery,charger){
    const fastCharge = battery*0.85/charger
    const decreasingCharge = battery*0.1/charger/0.5
    const trickleCharge = battery*0.05/charger/0.2

    const sumCharge = fastCharge+decreasingCharge+trickleCharge
    return parseFloat(sumCharge.toFixed(2))
}