class Solution {public:    string countAndSay(int n) {        vector<int> num;        num2digit(1, num);        vector<int> tmp;        for (int i = 1; i<n; i++) {            int last = num[0];            int cur  = last;            int count= 1;            for (int i=1; i < num.size(); i++) {                cur = num[i];                if (cur != last) {                    num2digit(count, tmp);                    tmp.push_back(last);                    last = cur;                    count = 1;                } else {                    count++;                }            }                        num2digit(count, tmp);            tmp.push_back(cur);            swap(num, tmp);            tmp.clear();        }        string res;        for (int i=0; i<num.size(); i++) {            res.push_back((char)(num[i] + ‘0‘));        }        return res;    }    void num2digit(int n, vector<int> &digits) {        vector<int> res;        if (n < 0) {            n = -n;        }        do {            res.push_back(n % 10);            n /= 10;        } while (n != 0);        for (int i=res.size() - 1; i >= 0; i--) {            digits.push_back(res[i]);        }    }};