题目描述
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
代码
#include <iostream>
#include <string>
using namespace std;
int main() {
string d;
int n, k;
cin >> d >> n;
for (int i = 1; i < n; i++) {
string t;
for (int j = 0; j < d.size(); j = k) {
for (k = j; k < d.size() && d[j] == d[k]; k++);
t += d[j] + to_string(k - j);
}
d = t;
}
cout << d;
return 0;
}
