PAT 1140 Look-and-say Sequence

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> //水题
using namespace std;
int main(){
	string d;
	int n;
	cin>>d>>n;
	for(int i=1; i<n; i++){
		char c=d[0];
		string t;
		int cnt=0;
		for(int j=0; j<d.size(); j++){
			if(d[j]==c) cnt++;
			else{
				t.append(1, c);
				t.append(1, cnt+'0');
				cnt=1;
				c=d[j];	
			}
		}
		t.append(1, c);
		t.append(1, cnt+'0');
		d=t;
	}
	cout<<d<<endl;
	return 0;
}