题解 | #DNA序列#

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(in.hasNext()){
            String str = in.next();
            int n = in.nextInt();
            //找到所有字串  有条件加入
            //查找所有字串的CG比例
            //输出最高的CG比例的子串
            int max_ratio=0;
            int flag=0;
            for(int i=0;i<str.length()-n+1;i++){
                int ratio = 0;
                String sub_str = str.substring(i,i+n);
                for(int j=0;j<n;j++){
                    if(sub_str.substring(j,j+1).equals("C")||sub_str.substring(j,j+1).equals("G"))
                        ratio++;
                }
                if(ratio>max_ratio){
                    max_ratio = ratio;
                    flag = i;
                }
            }
            System.out.println(str.substring(flag,flag+n));
        }
    }
}