剑指 Offer 58.左旋转字符串

# Python3代码：
def reverseLeftWords1(s, n):
    return s[n:] + s[:n]


s = "abcdefg"
n = 2
print(reverseLeftWords1(s, n))
# cdefgab

//Go代码：
func reverseLeftWords1(s string, n int) string {
  return s[n:] + s[:n]
}

# Python3代码：
def reverseLeftWords2(s, n):
    res = []
    for i in range(n, len(s)):
        res.append(s[i])
    for i in range(n):
        res.append(s[i])
    return "".join(res)


s = "90uisadjpa"
n = 2
print(reverseLeftWords2(s, n))
# uisadjpa90

# python3代码：
def reverseLeftWords3(s, n):
    res = ""
    for i in range(n, len(s)):
        res += s[i]
    for i in range(n):
        res += s[i]
    return res
    
# 遇到到尾端就要从头开始 的，基本都可以用取余的方法
def reverseLeftWords4(s, n):
    res = ""
    for i in range(n, n + len(s)):
        res += s[i % len(s)]  # 用取余来找下标
    return res

s = "1111yiyi"
n = 4
print(reverseLeftWords3(s, n))
print(reverseLeftWords4(s, n))
# yiyi1111

//Go代码：
func reverseLeftWords2(s string, n int) string {
  str1 := ""
  str2 := ""
  for i := 0; i < len(s); i++{
    if i < n{
      str1 += string(s[i])
    }else {
      str2 += string(s[i])
    }
  }
  return str2 + str1
}

func main()  {
  s := "900abcdefg"
  n := 3
  //println(reverseLeftWords1(s, n))
  println(reverseLeftWords2(s, n))
}
//abcdefg900