The sword refers to offer 2. Replace space (String)

Title Description

Implement a function that replaces each space in a string with "%20". For example, when the string is we are Happy. The string after substitution is we%20are%20happy.

Title Address

https://www.nowcoder.com/practice/4060ac7e3e404ad1a894ef3e17650423?tpId=13&tqId=11155&tPage=1&rp=2 &ru=%2fta%2fcoding-interviews&qru=%2fta%2fcoding-interviews%2fquestion-ranking

Idea 1: Open a new string, traverse the given string, and add a% 20 after the new string when the character is a space, otherwise, add the original character

Idea 2: Convert a string to a list, traverse a string, and, in turn, add '% ', ' 2 ', ' 0 ' to the list after the character is a space; otherwise, add the original character

Idea 3: If you add '%20 ' every time you encounter a space, the number behind the space needs to be moved back frequently. With this kind of moving problem, we can try to give the final desired length, then scan backwards, and then given two pointers to ensure the positioning.

Python

#-*-coding:utf-8-*-classSolution:#s Source string    defReplacespace (self, s):#Write code here        ifLen (s) = =0:return "'        #Idea 1        #newstring = ' '        #For I in S:        #if i = = ':        #newstring + = '%20 '        #Else:        #newstring + = i        #return newstring        #Idea 2:        #lis = List (s)        #newlis = []        #For i in LIS:        #if i = = ':        #newlis.append ('% ')        #newlis.append (' 2 ')        #newlis.append (' 0 ')        #Else:        #newlis.append (i)        #return "". Join (Newlis)        #Idea 3Count =0 forIinchS:ifi = =' ': Count+ = 1Newlen= Len (s) + count * 2Newstr= Newlen *[None] indexofnew, Indexofori= Len (newstr)-1, Len (s)-1 whileIndexofnew >= 0 andIndexofnew >=Indexofori:ifS[indexofori] = =' ': Newstr[indexofnew-2:INDEXOFNEW+1] = ['%','2','0'] Indexofnew-= 3Indexofori-= 1Else: Newstr[indexofnew]=S[indexofori] Indexofnew-= 1Indexofori-= 1return "". Join (NEWSTR)if __name__=='__main__': Result= Solution (). Replacespace ('We are happy.')    Print(Result)

The sword refers to offer 2. Replace space (String)