java朴素解法

很朴素的解法

感觉也没有别的
复杂度O(NK)

import java.util.*;
import java.io.*;
public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String in;
        while((in = br.readLine())!=null){
            int w= Integer.parseInt(br.readLine());//输入窗口大小
            System.out.println(getString(in,w));
        }
    }
    public static String getString(String in,int w){
        int maxLen=0;
        String res="";
        for(int i=0;i<in.length()-w+1;i++){
            int tmp=countSubString(in.substring(i,i+w));
            if(tmp>maxLen){
                maxLen=tmp;
                res=in.substring(i,i+w);
            }
        }

        return res;
    }
    public static int countSubString(String in){
        int count=0;
        for(int i=0;i<in.length();i++){
            if(in.charAt(i)=='C'||in.charAt(i)=='G')
                count++;
        }
        return count;
    }
}