剑指offer——替换空格

# -*- coding:utf-8 -*-
class Solution:
    # s 源字符串
    def replaceSpace(self, s):
        # write code here
        
        # 方法一：replace
        # return s.replace(' ','%20')
        
        # 方法二：append
        a = []
        for i in range(len(s)):
            if s[i] == ' ':
                a.append('%20')
            else:
                a.append(s[i])
        return ''.join(a)