题解 | #DNA序列#

import java.util.*;

// 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 sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String sequence = sc.nextLine();
            int n = Integer.parseInt(sc.nextLine());
            List<String> gcList = new ArrayList<>();
            int start = 0;
            int end = n;
            while (end <= sequence.length()) {
                String gc = sequence.substring(start, end);
                gcList.add(gc);
                start ++;
                end ++;
            }
            int max = Integer.MIN_VALUE;
            String gcRatio = "";
            for (String gc : gcList) {
                int len = gc.replace("A", "").replace("T", "").length();
                if (len > max) {
                    max = len;
                    gcRatio = gc;
                }
            }
            System.out.println(gcRatio);
        }
    }
}