Reverse words in a string

Https://leetcode.com/problems/reverse-words-in-a-string/

Given an input string, reverse the string word by word.

For example,
Given S ="the sky is blue",
Return"blue is sky the".

Update ):
For C programmers: try to solve itIn-PlaceInO(1) space.

Click to show clarification.

Clarification:

 

• What constitutes a word?
  A sequence of non-space characters constitutes a word.
• Cocould the input string contain leading or trailing spaces?
  Yes. However, your reversed string shocould not contain leading or trailing spaces.
• How about multiple spaces between two words?
  Reduce them to a single space in the reversed string.

 

 1 import java.util.ArrayList; 2 import java.util.List; 3 import java.util.Stack; 4  5 public class Solution { 6     public static String reverseWords(String s) { 7     List<String> li=new ArrayList(); 8         int len0=s.length(); 9         int len1=0;10         String x="";11         for(int i=0;i<len0;i++){12             char c=s.charAt(i);13             if(c!=‘ ‘) x+=c;14             else{15             if(x.length()!=0){16                 len1++;17                 li.add(x);18             }19             x="";20             }21         }22         if(x.length()!=0) li.add(x);23         Stack<String>st=new Stack();24         for(String str:li){25             st.add(str);26         }27         s="";28         while(!st.isEmpty()){29             s+=st.pop();30             if(st.size()!=0)31             s+=" ";32         }33         return s;34     }35     public static void main(String[]args){36     System.out.println(reverseWords("   a   b "));37     }38 }

 

Reverse words in a string