题解 | #DNA序列#

滑动窗口

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);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNext()) { // 注意 while 处理多个 case
            String b = in.nextLine();
            int a = in.nextInt();
            System.out.println(findGc(b, a));
        }
    }
    public static String findGc(String str, int length) {
        if (str.length() == length) {
            return str;
        }
        String result = null;
        int maxCount = 0;
        for (int i = 0; i < str.length() - length; i++) {
            String temp = str.substring(i, i + length);
            if (maxCount < countGc(temp)) {
                maxCount = countGc(temp);
                result = temp;
            }
        }
        return result;
    }
    public static int countGc(String str) {
        int result = 0;
        for (int i = 0; i < str.length(); i++) {
            if (str.charAt(i) == 'G' || str.charAt(i) == 'C') {
                result = result + 1;
            }
        }
        return result;
    }
}