kata-harrypotter.go

kata-harrypotter.go

package main

import (
	"fmt"
	"sort"
)

var BOOK_PRICE = 8

var priceMultiplier = map[int]float32{
	1: 1,
	2: .95,
	3: .9,
	4: .8,
	5: .75,
}

func main() {
	testBasics()
	testSimpleDiscounts()
	testSeveralDiscounts()
	testEdgeCases()
}

func testBasics() {
	assert_equal(0, price([]int{}...))
	assert_equal(8, price([]int{0}...))
	assert_equal(8, price([]int{1}...))
	assert_equal(8, price([]int{2}...))
	assert_equal(8, price([]int{3}...))
	assert_equal(8, price([]int{4}...))
	assert_equal(8*2, price([]int{0, 0}...))
	assert_equal(8*3, price([]int{1, 1, 1}...))
}

func testSimpleDiscounts() {
	assert_equal(8*2*0.95, price([]int{0, 1}...))
	assert_equal(8*3*0.9, price([]int{0, 2, 4}...))
	assert_equal(8*4*0.8, price([]int{0, 1, 2, 4}...))
	assert_equal(8*5*0.75, price([]int{0, 1, 2, 3, 4}...))
}

func testSeveralDiscounts() {
	assert_equal(8+(8*2*0.95), price([]int{0, 0, 1}...))
	assert_equal(2*(8*2*0.95), price([]int{0, 0, 1, 1}...))
	assert_equal((8*4*0.8)+(8*2*0.95), price([]int{0, 0, 1, 2, 2, 3}...))
	assert_equal(8+(8*5*0.75), price([]int{0, 1, 1, 2, 3, 4}...))
}

func testEdgeCases() {
	assert_equal(2*(8*4*0.8), price([]int{0, 0, 1, 1, 2, 2, 3, 4}...))
	assert_equal(3*(8*5*0.75)+2*(8*4*0.8),
		price([]int{0, 0, 0, 0, 0,
			1, 1, 1, 1, 1,
			2, 2, 2, 2,
			3, 3, 3, 3, 3,
			4, 4, 4, 4}...))
}

func assert_equal(a float32, b float32) {
	if a != b {
		fmt.Printf("%f is not equal to %f\n", a, b)
		return
	}

	fmt.Printf("Test passed for %f\n", a)
}

func price(ints ...int) float32 {
	var sum float32 = 0
	books := []int{0, 0, 0, 0, 0}

	for _, item := range ints {
		books[item]++
	}

	sort.Ints(books)
	differentBooksCount := len(books)

	for i := 0; i < differentBooksCount; i++ {
		amount := books[i]
		multiplier := differentBooksCount - i
		sum += float32(multiplier) * float32(amount) * float32(BOOK_PRICE) * priceMultiplier[multiplier]
		//fmt.Println(float32(multiplier), float32(amount), float32(BOOK_PRICE), priceMultiplier[multiplier])

		for j := i; j < differentBooksCount; j++ {
			books[j] -= amount
		}
	}

	return sum
}