• 位运算

func reverseString(s []byte)  {
    l := 0
    r := len(s) - 1
    for l < r {
        s[l] ^= s[r]
        s[r] ^= s[l]
        s[l] ^= s[r]
        l++
        r--
    }
}

• 没技巧

func reverseStringRange(s []byte, l int, r int) {

	if r >= len(s) {
		r = len(s) - 1
	}
	for l < r {
		s[l] ^= s[r]
		s[r] ^= s[l]
		s[l] ^= s[r]
		l++
		r--
	}
}
func reverseStr(s string, k int) string {
	res := []byte(s)
	count := 0
	for i := 0; i < len(s); i += 2 * k {
		reverseStringRange(res, i, i+k-1)
		count++
	}
	return string(res)
}

def isNumber(c):
    return c >= '0' and c <= '9'

s = input()
res = []
for c in s:
    res.append("number" if isNumber(c) else c)
print("".join(res))

func reverseStringArr(s []string) {
	l := 0
	r := len(s) - 1
	for l < r {
		temp := s[l]
		s[l] = s[r]
		s[r] = temp
		l++
		r--
	}
}
func reverseWords(s string) string {
	chars := []byte(s)
	temp := ""
	var resArr []string
	// 分词
	for _, char := range chars {
		if char == ' ' {
			if temp != "" {
				resArr = append(resArr, temp)
			}
			temp = ""
			continue
		}
		temp = temp + string(char)
	}
    if temp != "" {
		resArr = append(resArr, temp)
	}
	// 反转
	reverseStringArr(resArr)
	// 拼接
	res := ""
	for i, s := range resArr {
		res += s
		if i != len(resArr)-1 {
			res += " "
		}
	}
	return res
}

• SB版

n = int(input(""))
s = input("")

print(s[-n:]+s[:-n])

• NB版

n = int(input(""))
s = input("")
    
r = len(s) - 1
reverse(s, 0, r-n)
reverse(s, r-n, r)
reverse(s, 0, r)
print(s[-n:]+s[:-n])