leetcode 日经贴，Cpp code -Summary Ranges

Summary Ranges

class Solution {public:    string i2s(long long n) {        string ret, neg;        if (n < 0) {            neg = "-";            n = -n;        }        if (n == 0) {            return "0";        }        while (n) {            ret = char('0' + n % 10) + ret;            n /= 10;        }        return neg + ret;    }        vector<string> summaryRanges(vector<int>& nums) {        vector<string> summary;        int st = 0;        for (int i = 1; i <= nums.size(); ++i) {            if (i == nums.size() || nums[i] != nums[i - 1] + 1) {                if (st < i - 1) {                    summary.push_back(i2s(nums[st]) + "->" + i2s(nums[i - 1]));                } else {                    summary.push_back(i2s(nums[st]));                }                st = i;            }        }        return summary;    }};