LeetCode-Reverse Words in a String[AC源码]

 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 Submissions
10  *         Given an input string, reverse the string word by word.
11  * 
12  *         For example
13  *             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 LiuWei
25  * @Date 2014年8月15日下午7:48:48
26  * @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 space
50         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 space
72         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 }