python实现剑指offer系列2：字符串空格替换

牛客网题目链接：https://www.nowcoder.com/practice/4060ac7e3e404ad1a894ef3e17650423?tpId=13&tqId=11155&tPage=1&rp=1&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking
题目：请实现一个函数，将一个字符串中的空格替换成“%20”。例如，当字符串为We Are Happy.则经过替换之后的字符串为We%20Are%20Happy。

代码实现：

class Solution:    # s 源字符串    def replaceSpace(self, s):        newstr = ''        times = 0        iden = []        for i in range(len(s)):            if s[i]==' ':                times += 1                iden.append(i)        for j in range(len(s)):            if j in iden:                newstr = newstr + '%20'            else:                newstr = newstr + s[j]        return newstr        # write code here