单词接龙

import java.util.*; public class Main {

public static void main(String[] args){
    Scanner in = new Scanner(System.in);
    while(in.hasNext()){
        int k = Integer.parseInt(in.next());
        int n = Integer.parseInt(in.next());
        String[] arr = new String[n];
        for(int i=0; i<n; i++){
            arr[i] = in.next();
        }
        System.out.println(JL(arr, k));
    }
}

public static String JL(String[] arr, int k){
    StringBuilder sb = new StringBuilder();
    sb.append(arr[k]);
    Arrays.sort(arr, new Comparator<String>() {
        @Override
        public int compare(String o1, String o2) {
            if(o1.charAt(0) == o2.charAt(0)){
                if(o1.length() != o2.length()){
                    return o2.length() - o1.length();
                } else {
                    return o1.compareTo(o2);
                }
            }
            return o1.compareTo(o2);
        }
    });
    boolean[] flag = new boolean[arr.length];
    for(int i=0; i<arr.length; i++){
        if(arr[i].equals(sb.toString())){
            flag[i] = true;
            break;
        }
    }
    boolean hasNext = true;
    while(hasNext){
        hasNext = false;
        for(int i=0; i<arr.length; i++){
            if(flag[i]) continue;
            if(arr[i].charAt(0) == sb.charAt(sb.length()-1)){
                sb.append(arr[i]);
                flag[i] = true;
                hasNext = true;
                break;
            }
        }
    }

    return sb.toString();
}

}