Q2:Reverse Words in a String

Clarification:

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

MyAnswer 1 (Java):

 1 public class Solution {
 2     public String reverseWords(String s) {
 3         String result = "";
 4         int i = 0;
 5         int j = s.length();
 6         for(i = s.length()-1; i >= 0; i--)
 7         {
 8             if(s.charAt(i) == ‘ ‘)
 9             {
10                 if(i == s.length()-1)
11                 {
12                     j = i;
13                     //continue;
14                 }
15                 else if(i == 0)
16                 {
17                     //i++;
18                     break;
19                 }
20                 else if(j == i+1)
21                 {
22                     j = i;
23                     //continue;
24                 }
25                 else
26                 {
27                     result = result.concat(s.substring(i+1,j)+" ");
28                     j = i;
29                 }
30             }
31         }
32         result = result.concat(s.substring(i+1,j));
33         if(!result.isEmpty() && result.charAt(result.length()-1) == ‘ ‘)
34             result = result.substring(0,result.length()-1);
35         return result;
36     }
37 }

使代码更加精简，改为：

MyAnswer 2(Java):

 1 public class Solution {
 2     public String reverseWords(String s) {
 3
 4         String result = "";
 5         int j = s.length();
 6         int i = j-1;
 7
 8         for(; i >= 0; i--)
 9         {
10             if(s.charAt(i) == ‘ ‘)
11             {
12                 if(i == 0)
13                 {
14                     break;
15                 }
16                 else if(i != s.length()-1 && j != i+1)
17                 {
18                     result = result.concat(s.substring(i+1,j)+" ");
19                 }
20                 j = i;
21             }
22         }
23
24         result = result.concat(s.substring(i+1,j));
25
26         int k = result.length();
27         if(!result.isEmpty() && result.charAt(k-1) == ‘ ‘)
28             result = result.substring(0,k-1);
29         return result;
30     }
31 }