LeetCode – Refresh – Count and Say

class Solution {
public:
string getNext(string s) {
ostringstream oss;
char rec = s[0];
int len = s.size(), num = 1;
for (int i = 1; i < len; i++) {
if (rec != s[i]) {
oss << char(num + '0') << rec;
rec = s[i];
num = 1;
} else num++;
}
oss << char(num + '0') << rec;
return oss.str();
}
string countAndSay(int n) {
string result = "1";
for (int i = 2; i <= n; i++) {
result = getNext(result);
}
return result;
}
};