【LeetCode 228_数组】Summary Ranges

 vector<string> summaryRanges(vector<int>& nums)
 {
     int nums_len = nums.size();
     vector<string> res;
     if (nums_len == )
         return res;

     for (int i = ; i < nums_len;) {
         int start = i, end = i;
         while (end +  < nums_len && nums[end + ] == nums[end] + ) end++;
         if (end > start)
             res.push_back(to_string(nums[start]) + "->" + to_string(nums[end]));
         else
             res.push_back(to_string(nums[start]));
         i = end + ;
     }
     return res;
 }