1 package com.lw.leet1; 2  3 import java.util.Stack; 4  5 /** 6  * @ClassName:Solution 7  * @Description: 8  *         Reverse Words in a String  9  *         Total Accepted: 26194 Total Submissions: 187094 My Submissions10  *         Given an input string, reverse the string word by word.11  * 12  *         For example13  *             Given s = "the sky is blue"14  *             return "blue is sky the".15  * 16  *         Clarification:17  *             What constitutes a word?18  *             A sequence of non-space characters constitutes a word.19  *         Could the input string contain leading or trailing spaces?20  *             Yes. However, your reversed string should not contain leading or trailing spaces.21  *         How about multiple spaces between two words?22  *             Reduce them to a single space in the reversed string.23  * 24  * @Author LiuWei25  * @Date 2014年8月15日下午7:48:4826  * @Mail nashiyue1314@163.com 27  */28 public class Solution {29     30     public String reverseWords(String word){31         Stack<String> sstack = new Stack<String>();32         int flag = 0;33         for(int i= 0; i<word.length(); i++){34             while(i<word.length() && word.charAt(i)==‘ ‘){35                 i++;36             }37             flag = i;38             while(i<word.length() && word.charAt(i)!=‘ ‘){39                 i++;40             }41             if(flag != i){42                 sstack.push(word.substring(flag, i));43             }44         }45         String res = "";46         while(!sstack.isEmpty()){47             res += sstack.pop()+" ";48         }49 //        The input string which is made up of space50         if(res.length()==0){51             return "";52         }53         return res.substring(0, res.length()-1);54     }55     56     public String reverseWords2(String word){57         String res ="";58         int flag = 0;59         for(int i= 0; i<word.length(); i++){60             while(i<word.length() && word.charAt(i)==‘ ‘){61                 i++;62             }63             flag = i;64             while(i<word.length() && word.charAt(i)!=‘ ‘){65                 i++;66             }67             if(flag != i){68                 res = word.substring(flag, i)+" "+res;69             }70         }71 //        The input string which is made up of space72         if(res.length()==0){73             return "";74         }75         return res.substring(0, res.length()-1);76     }77     78     public static void main(String[] args){79         Solution s = new Solution();80         System.out.println(s.reverseWords2("   hello world    "));81     }82 }