From LeetCode 151. Reverse Words in a String

Description

Given an input string s, reverse the order of the words.

A word is defined as a sequence of non-space characters. The words in s will be separated by at least one space.

Return a string of the words in reverse order concatenated by a single space.

Note that s may contain leading or trailing spaces or multiple spaces between two words. The returned string should only have a single space separating the words. Do not include any extra spaces.

Solution1: use split

class Solution:
    def reverseWords(self, s: str) -> str:
        s = s.split()
        left, right = 0, len(s) - 1
        
        while left < right:
            s[left], s[right] = s[right], s[left]
            left += 1
            right -= 1
            
        return ' '.join(s)

Solution2:

class Solution:
  #1.去除多余的空格
        def trim_spaces(self,s):     
            n=len(s)
            left=0
            right=n-1
        
            while left<=right and s[left]==' ':       #去除开头的空格
                left+=1
            while left<=right and s[right]==' ':        #去除结尾的空格
                right=right-1
            tmp=[]
            while left<=right:                                    #去除单词中间多余的空格
                if s[left]!=' ':
                    tmp.append(s[left])
                elif tmp[-1]!=' ':                                  #当前位置是空格，但是相邻的上一个位置不是空格，则该空格是合理的
                    tmp.append(s[left])
                left+=1
            return tmp
#2.翻转字符数组
        def reverse_string(self,nums,left,right):
            while left<right:
                nums[left], nums[right]=nums[right],nums[left]
                left+=1
                right-=1
            return None
#3.翻转每个单词
        def reverse_each_word(self, nums):
            start=0
            end=0
            n=len(nums)
            while start<n:
                while end<n and nums[end]!=' ':
                    end+=1
                self.reverse_string(nums,start,end-1)
                start=end+1
                end+=1
            return None

#4.翻转字符串里的单词
        def reverseWords(self, s): #测试用例："the sky is blue"
            l = self.trim_spaces(s)                     #输出：['t', 'h', 'e', ' ', 's', 'k', 'y', ' ', 'i', 's', ' ', 'b', 'l', 'u', 'e'
            self.reverse_string( l,  0, len(l) - 1)   #输出：['e', 'u', 'l', 'b', ' ', 's', 'i', ' ', 'y', 'k', 's', ' ', 'e', 'h', 't']
            self.reverse_each_word(l)               #输出：['b', 'l', 'u', 'e', ' ', 'i', 's', ' ', 's', 'k', 'y', ' ', 't', 'h', 'e']
            return ''.join(l)                                 #输出：blue is sky the