1140 Look-and-say Sequence （20 分）

Look-and-say sequence is a sequence of integers as the following:

D, D1, D111, D113, D11231, D112213111, ...

where D is in [0, 9] except 1. The (n+1)st number is a kind of description of the nth number. For example, the 2nd number means that there is one D in the 1st number, and hence it is D1; the 2nd number consists of one D (corresponding to D1) and one 1 (corresponding to 11), therefore the 3rd number is D111; or since the 4th number is D113, it consists of one D, two 1's, and one 3, so the next number must be D11231. This definition works for D = 1 as well. Now you are supposed to calculate the Nth number in a look-and-say sequence of a given digit D.

Input Specification:

Each input file contains one test case, which gives D (in [0, 9]) and a positive integer N (≤ 40), separated by a space.

Output Specification:

Print in a line the Nth number in a look-and-say sequence of D.

Sample Input:

1 8

Sample Output:

1123123111

 #include<bits/stdc++.h>
using namespace std;
int main()
{
    string s;
    int n;
    cin>>s>>n;
    for(int i=0;i<n-1;i++)
    {
        int count=1;
        string ans;
        for(int j=0;j<s.length();j++)
        {
            if(s[j]==s[j+1])
                count++;
            else
            {
                ans+=s[j];
                ans+=to_string(count);
                count=1;
            }
        }
        s = ans;
    }
    cout<<s;
}