reverseStringTwoPointers.go

package main

import (
	"fmt"
	"regexp"
	"strings"
)

func reverseString(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 reverseWords(s string) string {
	space := regexp.MustCompile(`\s+`)
	s = space.ReplaceAllString(s, " ")
	ret := []string{}
	reversedS := reverseString(s) // "rab ooF"

	start := 0
	end := 0
	for i, r := range reversedS {
		lastChar := i == len(reversedS)-1
		if r == 32 || lastChar {
			if lastChar {
				end = i + 1
			} else {
				end = i
			}
			reversedWord := reversedS[start:end]
			unreversedString := reverseString(string(reversedWord))
			ret = append(ret, unreversedString)
			start = i + 1
		}
	}
	return strings.Join(ret, " ")
}

func main() {
	fmt.Printf("**%s**", reverseWords("Hello     World!"))
}