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"].

Credits:
Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

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silu: Pay more attention to the corner case.

public class Solution {    public List<String> summaryRanges(int[] nums) {        List<String> ret = new ArrayList<String>();        int len = nums.length;        if(len < 1)            return ret;        StringBuilder buffer = new StringBuilder();        for(int i = 0; i < nums.length; i++){            buffer.append(nums[i]);            if(i < len - 1 && nums[i] + 1 == nums[i + 1]){                buffer.append("->");                while(i < len - 1 && nums[i] + 1 == nums[i + 1]){                    i++;                }                buffer.append(nums[i]);            }            ret.add(buffer.toString());            buffer = new StringBuilder();        }        return ret;    }}