1140 Look-and-say Sequence (20分)

看数列生成算法

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本文介绍了一种基于特定数字D的看数列生成算法。该算法通过描述前一个数字符号出现的次数来生成序列中的下一个数。输入为数字D（0到9之间）和正整数N（不超过40），输出为看数列中第N个数。通过迭代过程，每次迭代都生成序列中的下一个数，直到达到指定的N为止。

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<iostream>
#include<vector>
#include<cstdlib>
using namespace std;

int main(){

    int d, n;
    cin >> d >> n;

    string s = to_string(d);

    for(int j = 0; j < n - 1; j++){

        string temp_s = "";
        char c = s[0];
        int count = 1;
        for(int i = 1; i < s.size(); i++){
            
            if(c == s[i]){
                count++;
            }else
            {
                // cout << c << " " << count << endl;
                temp_s += c;
                temp_s += to_string(count);
                count = 1;
                c = s[i];
            }
            


        }

        // cout << c << " " << count << endl;

        temp_s += c;
        temp_s += to_string(count);
        s = temp_s;

    

    }
    
    cout << s << endl;

 





    


    return 0;
}