LeetCode 228. Summary Ranges

class Solution {
public:
    vector<string> summaryRanges(vector<int>& nums) {
        
        vector<string> ans;
        
        if(nums.size()==0)
            return ans;
        
        int left=nums[0];
        int right;
        string str="";
        for(int i=1;i<nums.size();i++)
        {
            if(nums[i]!=nums[i-1]+1)
            {
                right=nums[i-1];
                str+=to_string(left);
                if(left!=right)
                {
                    str+="->";
                    str+=to_string(right);
                }
                
                left=nums[i];
                ans.push_back(str);
                str="";
            }
        }
        
        right=nums[nums.size()-1];
        str+=to_string(left);
        if(left!=right)
        {
            str+="->";
            str+=to_string(right);
        }
        ans.push_back(str);
        
        return ans;
        
    }
};