代码随想录05：字符串

反转字符串

输入：hello文章源自十年又十年-https://www.bbigsun.com/411.html

输出：olleh文章源自十年又十年-https://www.bbigsun.com/411.html

思路：双指针法，头尾双指针，互相交换，然后向中间平移，当头尾指针相交时结束文章源自十年又十年-https://www.bbigsun.com/411.html

def reverse(s):
    first = 0
    end = len(s)-1
    while first < end:
        s[first], s[end] = s[end],s[first]
        first += 1
        end -= 1

另外一种：文章源自十年又十年-https://www.bbigsun.com/411.html

s = s[::-1]

替换空格

输入："Hello World"
输出："Hello%20World"文章源自十年又十年-https://www.bbigsun.com/411.html

做题的做法：文章源自十年又十年-https://www.bbigsun.com/411.html

s = "20%".join(s.split(" "))

善用切片文章源自十年又十年-https://www.bbigsun.com/411.html 文章源自十年又十年-https://www.bbigsun.com/411.html