LeetCode(228) 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;
        auto start=nums.begin();

        while(start != nums.end())
        {
            auto end=start;
            end++;
            string tem="";
            int x=*start;
            itos(tem,x);
            while(end != nums.end() && *end - *start == 1){
                start++;
                end++;
            }
            if(x == *start)
                res.push_back(tem);
            else
            {
                tem+="->";
                itos(tem,*start);
                res.push_back(tem);
            }
            start++;
        }
        return res;
    }
    void itos(string &str,int k) //主要是如何快速转换成字符串！！！
    {
        ostringstream oss;//创建一个流

	    oss<<k;//把值传递如流中

	    str+=oss.str();
    }
};