[Codility] ParkingBill (Go)

https://app.codility.com/programmers/trainings/5/parking_bill/start/

Codility

 

Task description

You parked your car in a parking lot and want to compute the total cost of the ticket. The billing rules are as follows:

• The entrance fee of the car parking lot is 2;
• The first full or partial hour costs 3;
• Each successive full or partial hour (after the first) costs 4.

You entered the car parking lot at time E and left at time L. In this task, times are represented as strings in the format "HH:MM" (where "HH" is a two-digit number between 0 and 23, which stands for hours, and "MM" is a two-digit number between 0 and 59, which stands for minutes).

Write a function:

func Solution(E string, L string) int

that, given strings E and L specifying points in time in the format "HH:MM", returns the total cost of the parking bill from your entry at time E to your exit at time L. You can assume that E describes a time before L on the same day.

For example, given "10:00" and "13:21" your function should return 17, because the entrance fee equals 2, the first hour costs 3 and there are two more full hours and part of a further hour, so the total cost is 2 + 3 + (3 * 4) = 17. Given "09:42" and "11:42" your function should return 9, because the entrance fee equals 2, the first hour costs 3 and the second hour costs 4, so the total cost is 2 + 3 + 4 = 9.

Assume that:

• strings E and L follow the format "HH:MM" strictly;
• string E describes a time before L on the same day.

In your solution, focus on correctness. The performance of your solution will not be the focus of the assessment.

---

package solution

import (
	"time"
)

const parkingTimeLayout = "15:04"

func Solution(E string, L string) int {
    var result = 2

	eTime, _ := time.Parse(parkingTimeLayout, E)
	lTime, _ := time.Parse(parkingTimeLayout, L)
	difMin := lTime.Sub(eTime).Minutes()

	var isFirstTime = false
	var total int

	for difMin > 0 {
		if !isFirstTime {
			result += 3
			difMin -= 60
			isFirstTime = true
			continue
		}

		total++
		difMin -= 60
	}

	result += total * 4

	return result
}