foo:="Makan"
bar:="Makon"

foo:="Indah"
bar:="Ihkasyandehlo"

package main
import (
	"fmt"
	"unicode/utf8"
)
func commonBytes(s, t string) (bytes int) {
	if len(s) > len(t) {
		s, t = t, s
	}
	i := 0
	for ; i < len(s); i++ {
		if s[i] != t[i] {
			break
		}
	}
	return i
}
func commonRunes(s, t string) (runes int) {
	if len(s) > len(t) {
		s, t = t, s
	}
	i := 0
	for ; i < len(s); i++ {
		if s[i] != t[i] {
			break
		}
	}
	return utf8.RuneCountInString(s[:i])
}
func commonBytesRunes(s, t string) (bytes, runes int) {
	if len(s) > len(t) {
		s, t = t, s
	}
	i := 0
	for ; i < len(s); i++ {
		if s[i] != t[i] {
			break
		}
	}
	return i, utf8.RuneCountInString(s[:i])
}
func main() {
	Tests := []struct {
		word1, word2 string
	}{
		{"Makan", "Makon"},
		{"Indah", "Ihkasyandehlo"},
		{"日本語", "日本語"},
	}
	for _, test := range Tests {
		fmt.Println("Words:        ", test.word1, test.word2)
		fmt.Println("Bytes:        ", commonBytes(test.word1, test.word2))
		fmt.Println("Runes:        ", commonRunes(test.word1, test.word2))
		fmt.Print("Bytes & Runes: ")
		fmt.Println(commonBytesRunes(test.word1, test.word2))
	}
}

package main
import "fmt"
import "unicode/utf8"
func index(s1, s2 string) int {
	res := 0
	for i, w := 0, 0; i < len(s2); i += w {
		if i >= len(s1) {
			return res
		}
		runeValue1, width := utf8.DecodeRuneInString(s1[i:])
		runeValue2, width := utf8.DecodeRuneInString(s2[i:])
		if runeValue1 != runeValue2 {
			return res
		}
		if runeValue1 == utf8.RuneError || runeValue2 == utf8.RuneError {
			return res
		}
		w = width
		res = i + w
	}
	return res
}
func main() {
	foo := "日本本a語"
	bar := "日本本b語"
	fmt.Println(index(foo, bar))
	foo = "日本語"
	bar = "日otest"
	fmt.Println(index(foo, bar))
	foo = "\xF0"
	bar = "\xFF"
	fmt.Println(index(foo, bar))
}

package main
import (
	"fmt"
)
func equal(s1, s2 string) int {
	eq := 0
	if len(s1) > len(s2) {
		s1, s2 = s2, s1
	}
	for key, _ := range s1 {
		if s1[key] == s2[key] {
			eq++
		} else {
			break
		}
	}
	return eq
}
func main() {
	fmt.Println(equal("buzzfizz", "buzz"))
	fmt.Println(equal("Makan", "Makon"))
	fmt.Println(equal("Indah", "Ihkasyandehlo"))
}