Count and Say 数字统计

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

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

class Solution {
public:
    string countAndSay(int n) {
        
        string res="1";
        int k=1;
        while(k<n)
        {
            res=solve(res);
            k++;
        }
        return res;
    }
    
    string solve(string res)
    {
        string ans;
        char pre=res[0];
        int k=1;
        int i;
        for(i=1;i<res.length();i++)
        {
            if(pre==res[i])
            {
                k++;
            }
            else
            {
                char temp=k+'0';
                ans+=temp;
                ans+=pre;
                pre=res[i];
                k=1;
            }
        }
        char temp=k+'0';
        ans+=temp;
        ans+=pre;
        
        return ans;
    }
    
};