The count-and-say sequence is the sequence of integers beginning as follows: 1, 11, 21, 1211, 111221, ... http://leetcode.com/onlinejudge

leetcode_count_and_say.cpp

class Solution {
public:
    string countAndSay(int n) {
        string ret = "1";
        while (--n) {
            stringstream ss;
            int cnt = 0;
            for (int i = 0; i < ret.length(); ++i) {
                cnt++;
                if (i == ret.length() - 1 || ret[i] != ret[i + 1]) {
                    ss << cnt << ret[i];
                    cnt = 0;
                }
            }
            ss >> ret;
        }
        return ret;
    }
};