1140 Look-and-say Sequence（22行代码+详细注释）

分数 20

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作者 CHEN, Yue

单位 浙江大学

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

代码长度限制

16 KB

时间限制

400 ms

内存限制

64 MB

#include
using namespace std;
const int N=30;
string s;
int n;
int main(){
    cin>>s>>n;
    n--;//第n次，故只用执行n-1次 
    while(n--){
        string temp;//临时字符串，用于储存每次的结果 
        for(int i=0;i             int j=i+1;
            while(s[j]==s[j-1])j++;//获取连续的数字 
            string num=to_string(j-i);//记录数字个数 
            temp+=s[i]+num;//将当前连续的字母及其次数记录在temp中 
            i=j-1;//下一个数字 
        }
        s=temp;//每次更新s 
    }
    cout<     return 0;
}