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.

注意char * 和 string的区别。string是一个和vector类，本身是有大小的。如果只

string str;
str[0] = 'a';
str[1] = 'b';

是无法正常改变str的。

class Solution {
public:
    string countAndSay(int n) {
        string re;
        vector <int> se;
        se.push_back(1);
        if(n == 1)return "1";
        
        for(int i = 0 ; i < n-1 ;i++)se = nth(se);
        
        int j = 0;
        for(int i = 0 ; se.begin() + i != se.end() ; i++)
        {
            char temp = se[i] + '0';
            re = re + temp;
            j++;
        }
        return re;
    }
    vector<int> nth(vector<int> n )
    {
        vector<int>:: iterator  it;
        vector<int> re;
        it = n.begin();
        for(;it != n.end();)
        {
            int temp = *it;
            //cout<<temp<<endl;
            int num =1;
            it++;
            while(*it == temp && it!= n.end()){it++; num++;}
            
            re.push_back(num);
            re.push_back(temp);
        }
        return re;
    }
};