[Leetcode] 38 - Count and Say

class Solution {
public:
string countAndSay(int n) {
string res = "";
if (n < 0) return res;

res = "1";
int i = 1;
while (i < n) {
string temp = "";

char prev = '-';
int count = 0;
for (int j = 0; j < res.size(); ++j) {
if (prev != res[j]) {
if (prev != '-') {
temp.push_back('0' + count);
temp.push_back(prev);
}
prev = res[j];
count = 1;
} else {
++count;
}
}

temp.push_back('0' + count);
temp.push_back(prev);

++i;
res = temp;
}

return res;
}
};