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