Leetcode 228. Summary Ranges

原题：

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

Example 1:

Input: [0,1,2,4,5,7]
Output: ["0->2","4->5","7"]

Example 2:

Input: [0,2,3,4,6,8,9]
Output: ["0","2->4","6","8->9"]

解决方法：
每一次循环，都找到最后一个连续数，然后将这个范围加入到结果集中。

代码：

vector<string> summaryRanges(vector<int>& nums) {
        vector<string> res;
        for(int i = 0; i < nums.size();){
            int num = nums[i];
            while(i < nums.size() -1 && ((nums[i] + 1) == nums[i + 1]))
                ++i;
            if (num != nums[i]){
                res.push_back(to_string(num) + "->" + to_string(nums[i]));
            }else{
                res.push_back(to_string(num));
            }
            ++i;
        }
        return res;
    }