题解 | #DNA序列#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = in.next();
        char[] ch = s.toCharArray();
        int N = in.nextInt();
        int count = 0;
        int max = Integer.MIN_VALUE;
        String res = "";
        for (int i = 0; i <= ch.length - N; i++) {
            for (int j = i; j < i + N; j++) {
                if (ch[j] == 'G' || ch[j] == 'C')
                    count++;
            }
            if (count > max){
                max = count;
                res = s.substring(i, i+N);
            }
            count = 0;
        }
        System.out.println(res);
    }
}