Summary Ranges（两个指针）

Summary Ranges

  Total Accepted: 511   Total Submissions: 2271

Given a sorted integer array without duplicates, return the summary of its ranges.

For example, given [0,1,2,4,5,7], return ["0->2","4->5","7"].

[思路]

两个指针 start, end.  如果nums[end+1] = nums[end]+1, 就移动end指针, 否则, 插入字符串nums[start]->nums[end]. 

[CODE]

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1. public class Solution {  
2.     // [0,1,2,4,5,7], return ["0->2","4->5","7"].   
3.     public List<String> summaryRanges(int[] nums) {  
4.         List<String> res = new ArrayList<>();  
5.         if(nums==null || nums.length<1) return  res;  
6.           
7.         int s=0, e=0;  
8.         while(e<nums.length) {  
9.             if(e+1<nums.length && nums[e+1]==nums[e]+1) {  
10.                 e++;  
11.             } else {  
12.                 if(s==e) {  
13.                     res.add(Integer.toString(nums[s]));  
14.                 } else {  
15.                     String str = nums[s] + "->" + nums[e];  
16.                     res.add(str);  
17.                 }  
18.                 ++e;  
19.                 s = e;  
20.             }  
21.         }  
22.         return res;  
23.     }  
24. }