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"].

class Solution {
public:
    vector<string> summaryRanges(vector<int>& nums) {
        vector<string> res;
        if (nums.empty()) {
            return res;
        }
        int begin = 0, end = 1;
        while (begin < nums.size()) {
            if ((end < nums.size() && nums[end] != nums[end - 1] + 1) || end == nums.size()) {
                string range;
                if (end - begin == 1) {
                    range = to_string(nums[begin]);
                } else {
                    range = to_string(nums[begin]) + "->" + to_string(nums[end - 1]);
                }
                res.push_back(range);
                begin = end;
            }
            end++;
        }
       
        
        return res;
    }
};