剑指 替换空格

s.split

class Solution:
    def replaceSpace(self , s ):
        # write code here
        result=''
        for item in s.split(' '):
            result+=item
            result+='%20'


        return result[:-3]

s.replace

循环判断有空格

双指针

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param s string字符串 
# @return string字符串
#
class Solution:
    def replaceSpace(self , s ):
        # write code here

        if len(s)==0:
            return s
        else:
            s=list(s)
            count=0
            for item in s:
                if item==' ':
                    count+=1
            left=len(s)-1
            for i in range(count*2):
                s.append(' ')

            right=len(s)-1

            while left>=0:
                if s[left]==" ":
                    s[right-2:right+1]='%20'
                    right=right-3
                    left-=1
                else:
                    s[right]=s[left]
                    left-=1
                    right-=1
            str_s=''
            for item in s:
                str_s+=item
            return str_s