Roman To Integer Benchmarks

tmp_test.go

package main_test

import (
	"testing"
)

var res int

func a(x int) int {
	return x
}

func BenchmarkRoman(b *testing.B) {
	for _, benchCase := range []struct {
		name string
		f    func(s string) int
	}{
		{"map", romanToIntMap},
		{"array", romanToIntArr},
		{"arraySmallLocal", romanToIntArrSmallLocal},
		{"arrayLocal", romanToIntArrLocal},
		{"switch", romanToIntSwitch},
	} {
		b.Run(benchCase.name, func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				res = benchCase.f("MMMCMXCVIII")
				a(res)
				res = benchCase.f("LVIII")
				a(res)
				res = benchCase.f("IX")
				a(res)
				res = benchCase.f("MCMXCI")
				a(res)
			}
		})
	}
}

var romanMap = map[byte]int{'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}

func romanToIntMap(s string) int {
	var result = romanMap[s[len(s)-1]]

	for i := len(s) - 2; i >= 0; i-- {
		if romanMap[s[i]] < romanMap[s[i+1]] {
			result -= romanMap[s[i]]
		} else {
			result += romanMap[s[i]]
		}
	}
	return result
}

var romanArr = [...]int{'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}

func romanToIntArr(s string) int {
	var result = romanArr[s[len(s)-1]]

	for i := len(s) - 2; i >= 0; i-- {
		if romanArr[s[i]] < romanArr[s[i+1]] {
			result -= romanArr[s[i]]
		} else {
			result += romanArr[s[i]]
		}
	}
	return result
}

func romanToIntArrLocal(s string) int {
	var romanArr = [256]int{'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
	var result = romanArr[s[len(s)-1]]

	for i := len(s) - 2; i >= 0; i-- {
		if romanArr[s[i]] < romanArr[s[i+1]] {
			result -= romanArr[s[i]]
		} else {
			result += romanArr[s[i]]
		}
	}
	return result
}

func romanToIntArrSmallLocal(s string) int {
	var romanArrSmall = [...]int{
		'I' - 'C': 1,
		'V' - 'C': 5,
		'X' - 'C': 10,
		'L' - 'C': 50,
		'C' - 'C': 100,
		'D' - 'C': 500,
		'M' - 'C': 1000,
	}
	var result = romanArrSmall[s[len(s)-1]-'C']

	for i := len(s) - 2; i >= 0; i-- {
		if romanArrSmall[s[i]-'C'] < romanArrSmall[s[i+1]-'C'] {
			result -= romanArrSmall[s[i]-'C']
		} else {
			result += romanArrSmall[s[i]-'C']
		}
	}
	return result
}

func romanToIntSwitch(s string) int {
	var result = getVal(s[len(s)-1])

	for i := len(s) - 2; i >= 0; i-- {
		if getVal(s[i]) < getVal(s[i+1]) {
			result -= getVal(s[i])
		} else {
			result += getVal(s[i])
		}
	}
	return result
}

func getVal(s byte) int {
	switch s {
	case 'I':
		return 1
	case 'V':
		return 5
	case 'X':
		return 10
	case 'L':
		return 50
	case 'C':
		return 100
	case 'D':
		return 500
	case 'M':
		return 1000
	default:
		return 0
	}
}

$ go test -run=None -bench=./... -benchmem -cpuprofile=cpu.pprof .
goos: linux
goarch: amd64
pkg: github.com/sebnyberg/leetcode/tmp
cpu: Intel(R) Core(TM) i5-8500 CPU @ 3.00GHz
BenchmarkRoman/map-6                   1289235               921.8 ns/op             0 B/op          0 allocs/op
BenchmarkRoman/array-6                45800854                26.06 ns/op            0 B/op          0 allocs/op
BenchmarkRoman/arraySmallLocal-6      24761743                48.27 ns/op            0 B/op          0 allocs/op
BenchmarkRoman/arrayLocal-6            8292146               802.3 ns/op             0 B/op          0 allocs/op
BenchmarkRoman/switch-6               10335658               116.2 ns/op             0 B/op          0 allocs/op
PASS
ok      github.com/sebnyberg/leetcode/tmp       13.440s