Leetcode: Summary Ranges

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"].

这种题就是要写的clean and tidy，好方法：

 1 public class Solution {
 2     public List<String> summaryRanges(int[] nums) {
 3         List<String> res = new ArrayList<String>();
 4         if (nums==null || nums.length==0) return res;
 5         for (int i=0; i<nums.length; i++) {
 6             int temp = nums[i];
 7             while (i+1<nums.length && nums[i+1]==nums[i]+1) i++;
 8             if (temp == nums[i]) {
 9                 res.add(temp+"");
10             }
11             else {
12                 res.add(temp+"->"+nums[i]);
13             }
14         }
15         return res;
16     }
17 }

维护两个指针的方法：

 1 public class Solution {
 2     public List<String> summaryRanges(int[] nums) {
 3         List<String> res = new ArrayList<String>();
 4         if (nums == null || nums.length == 0) return res;
 5         int l= 0, r = 0;
 6         for (r=0; r<nums.length-1; r++) {
 7             if (nums[r] != nums[r+1]-1) {
 8                 if (nums[r] == nums[l]) res.add(nums[l] + "");
 9                 else res.add(nums[l] + "->" + nums[r]);
10                 l = r+1;
11             }
12         }
13         if (nums[r] == nums[l]) res.add(nums[l] + "");
14         else res.add(nums[l] + "->" + nums[r]);
15         return res;
16     }
17 }