Leetcode_Array_cpp/228. Summary Ranges.cpp at main · Bushraabir/Leetcode_Array_cpp · GitHub

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class Solution {
public:
    vector<string> summaryRanges(vector<int>& nums) {
        vector<string> res;
        if (nums.empty()) return res;

        int start = nums[0];   // start of current range
        int end = nums[0];     // end of current range

        for (int i = 1; i < nums.size(); ++i) {
            if (nums[i] == end + 1) {

                end = nums[i];
            } else {

                if (start == end) {
                    res.push_back(to_string(start));
                } else {
                    res.push_back(to_string(start) + "->" + to_string(end));
                }

                start = end = nums[i];
            }
        }


        if (start == end) {
            res.push_back(to_string(start));
        } else {
            res.push_back(to_string(start) + "->" + to_string(end));
        }

        return res;
    }
};