summary ranges

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.

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