parindromeかを判定する関数を複数パターン作って、一番早い書き方を調査

main.go

package main

import "unicode/utf8"

func Reverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}
	return string(runes)
}

func IsPalindrome(s string) bool {
	return s == Reverse(s)
}

func IsPalindrome2(s string) bool {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		if runes[i] != runes[j] {
			return false
		}
	}
	return true

}

func IsPalindrome3(s string) bool {
	l := len(s)
	for i, w := 0, 0; i < l; i += w {
		runeValue1, width := utf8.DecodeRuneInString(s[i:])
		runeValue2, width := utf8.DecodeLastRuneInString(s[:l-i])
		if runeValue1 != runeValue2 {
			return false
		}
		w = width
	}
	return true

}
func IsPalindrome4(s string) bool {
	l := len(s)
	for i, runeValue := range s {
		runeValue2, _ := utf8.DecodeLastRuneInString(s[:l-i])
		if runeValue != runeValue2 {
			return false
		}
	}
	return true
}

func main() {
	for i := 0; i < 1000000; i++ {
		IsPalindrome4("しんぶんし")
	}
}

main_test.go

package main

import "testing"

var s = "あいういあ"

func BenchmarkIsPalindrome(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome(s)
	}
}

func BenchmarkIsPalindrome2(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome2(s)
	}
}
func BenchmarkIsPalindrome3(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome3(s)
	}
}

func BenchmarkIsPalindrome4(b *testing.B) {
	for i := 0; i < b.N; i++ {
		IsPalindrome4(s)
	}
}
func TestIsKaibun(t *testing.T) {
	actual := IsPalindrome4(s)
	expected := true
	if actual != expected {
		t.Errorf("got %v\nwant %v", actual, expected)
	}
}
func TestIsKaibunFalse(t *testing.T) {
	actual := IsPalindrome4("あいういう")
	expected := false
	if actual != expected {
		t.Errorf("got %v\nwant %v", actual, expected)
	}
}

result

AMD FX-8120 3.1GHz[AM3+/8Core/125W]
memory 32GiB
ArchLinux

%  go version 
go version go1.4.1 linux/amd64

% go test -bench .
PASS
BenchmarkIsPalindrome	 3000000	       544 ns/op
BenchmarkIsPalindrome2	 5000000	       277 ns/op
BenchmarkIsPalindrome3	10000000	       202 ns/op
BenchmarkIsPalindrome4	10000000	       199 ns/op
ok  	_/home/masahito/src/golang/perindrome	8.287s