leetcode[38]Count and Say

The count-and-say sequence is the sequence of integers beginning as follows:

1, 11, 21, 1211, 111221, ...

1

is read off as

"one 1"

or

11

.

11

is read off as

"two 1s"

or

21

.

21

is read off as

"one 2

, then

one 1"

or

1211

.

Given an integer n, generate the nth sequence.

Note: The sequence of integers will be represented as a string.

class Solution {
public:
string next(string str)
{
int k=0;
string temp="0";
temp+=str[0];
int i;
for (i=1;i<str.size();i++)
{
if (str[i]==str[i-1])k++;
else
{
k++;
char temp1='0'+k;
temp+=temp1;
temp+=str[i-1];
k=0;
}
}
k++;
char temp1='0'+k;
temp+=temp1;
temp+=str[i-1];
return temp.substr(2,temp.size());
}
string countAndSay(int n)
{
string res="1";
for (int i=2;i<=n;i++)
{
res=next(res);
}
return res;
}
};