Summary Ranges

 1 // Accepted
 2     public List<String> summaryRanges(int[] nums) {
 3         
 4         List<String> result = new ArrayList<String>();
 5         if ( nums == null || nums.length <=0)
 6             return result;        
 7         
 8         int len = nums.length;
 9         
10         if( len == 1)
11         {
12             result.add(nums[0]+"");
13             return result;
14         }
15         int beginIndex = 0;
16         for(int i = 1; i < len ; i++)
17         {
18             if( nums[i] != nums[i-1] + 1)
19             {
20                 if(beginIndex != i-1)
21                 {
22                     result.add("" + nums[beginIndex] + "->" + nums[i-1]);
23                 }else{
24                     result.add("" + nums[i-1]);
25                 }
26                 beginIndex = i;
27             }
28         }
29         
30         if(beginIndex != len-1)
31         {
32             result.add("" + nums[beginIndex] + "->" + nums[len-1]);
33         }else{
34             result.add("" + nums[len-1]);
35         }
36         return result;    
37     }