题解 | #添加逗号#

• reverse

package main

import (
	"fmt"
	"strconv"
)

func reverse(s string) (result string) {
	for _, v := range s {
		result = string(v) + result
	}
	return 
}

func main() {
	var n int
	fmt.Scan(&n)

	s := strconv.Itoa(n)
	s = reverse(s)
	var res string
	for i := 0; i < len(s); i++ {
		if i%3 == 0 && i != 0 {
			res += ","
		}
		res += string(s[i])
	}
	fmt.Println(reverse(res))
}

• 利用 strings.Join

package main

import (
	"fmt"
	"strings"
)

func reverse(sl []string) {
	l,r := 0,len(sl)-1
	for l<r {
		sl[l],sl[r] = sl[r],sl[l]
		l++
		r--
	}
}

func main() {
	var n int
	fmt.Scan(&n)
	t := []string{}
	for n > 0 {
		var x string
		if n >= 1000 {
			x = fmt.Sprintf("%03d", n%1000)
		} else {
			x = fmt.Sprintf("%d", n%1000)
		}
		n /= 1000
		t = append(t, x)
	}
	reverse(t)
	fmt.Println(strings.Join(t, ","))
}