叫做……概括一个数组？

def summary_ranges(nums)
    summary = [];

    if nums.size == 0
        return summary
    end

    if nums.size == 1
        return summary << nums[0].to_s
    end

    head = nums[0]
    nums.each_index do |i|
        next if i == 0
        if nums[i] == nums.last && nums[i] != nums[i - 1] + 1 && head == nums[i - 1]
            summary << nums[i - 1].to_s
            summary << nums[i].to_s
        elsif nums[i] == nums.last && nums[i] != nums[i - 1] + 1 && head != nums[i - 1]
            summary << "#{head}->#{nums[i - 1]}"
            summary << nums[i].to_s
        elsif nums[i] == nums.last && nums[i] == nums[i - 1] + 1
            summary << "#{head}->#{nums[i]}"
        elsif nums[i] != nums[i - 1] + 1 && head == nums[i - 1]
            summary << nums[i - 1].to_s
            head = nums[i]
        elsif nums[i] != nums[i - 1] + 1 && head != nums[i - 1]
            summary << "#{head}->#{nums[i - 1]}"
            head = nums[i]
        end

    end
    summary
end

vector<string> summaryRanges(vector<int>& nums) {
    size_t len = nums.size();
    vector<string> summary;

    if (len == 0){
        return summary;
    }

    if (len == 1){
        summary.push_back(to_string(nums[0]));
        return summary;
    }

    auto begin = nums.front();
    for (size_t i = 1; i < len; ++i){
        if (nums[i] == nums.back() && nums[i] != nums[i - 1] + 1 && begin == nums[i - 1]){
            summary.push_back(to_string(nums[i - 1]));
            summary.push_back(to_string(nums[i]));
        }

        else if (nums[i] == nums.back() && nums[i] != nums[i - 1] + 1 && begin != nums[i - 1]){
            summary.push_back(to_string(begin) + "->" + to_string(nums[i - 1]));
            summary.push_back(to_string(nums[i]));
        }
        else if (nums[i] == nums.back() && nums[i] == (nums[i - 1] + 1)){
            summary.push_back(to_string(begin) + "->" + to_string(nums[i]));
        }
        else if (nums[i] != nums[i - 1] + 1 && begin == nums[i - 1]){
            summary.push_back(to_string(nums[i - 1]));
            begin = nums[i];
        }
        else if (nums[i] != nums[i - 1] + 1 && begin != nums[i - 1]){
            summary.push_back(to_string(begin) + "->" + to_string(nums[i - 1]));
            begin = nums[i];
        }
    }
    return summary;
}