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：

public class Solution {
    public List<String> summaryRanges(int[] nums) {
        List<String> res = new ArrayList<String>();
        if (nums==null || nums.length==0) return res;
        for (int i=0; i<nums.length; i++) {
            int temp = nums[i];
            while (i+1<nums.length && nums[i+1]==nums[i]+1) i++;
            if (temp == nums[i]) {
                res.add(temp+"");
            }
            else {
                res.add(temp+"->"+nums[i]);
            }
        }
        return res;
    }
}

 维护两个指针的方法：

public class Solution {
    public List<String> summaryRanges(int[] nums) {
        List<String> res = new ArrayList<String>();
        if (nums == null || nums.length == 0) return res;
        int l= 0, r = 0;
        for (r=0; r<nums.length-1; r++) {
            if (nums[r] != nums[r+1]-1) {
                if (nums[r] == nums[l]) res.add(nums[l] + "");
                else res.add(nums[l] + "->" + nums[r]);
                l = r+1;
            }
        }
        if (nums[r] == nums[l]) res.add(nums[l] + "");
        else res.add(nums[l] + "->" + nums[r]);
        return res;
    }
}