그래프를 ArrayList로 나타내기

package Chat;

import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.StringTokenizer;


public class asdf {
    public static void main(String[] args) throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(bf.readLine());

        int N = Integer.parseInt(st.nextToken());
        int M = Integer.parseInt(st.nextToken());

        ArrayList<Edge> graph[] = new ArrayList[N+1];
        for (int i = 1; i <= N; i++) {
            graph[i] = new ArrayList<>();
        }
        for (int i = 0; i < M; i++) {
            st = new StringTokenizer(bf.readLine());
            int startNode = Integer.parseInt(st.nextToken());
            int endNode = Integer.parseInt(st.nextToken());
            int value = Integer.parseInt(st.nextToken());

            graph[startNode].add(new Edge(endNode, value));
        }
        for (Edge edge : graph[1]) {
            System.out.println(edge.endNode + " " + edge.value);
        }
    }

}

class Edge{
    int endNode;
    int value;
    Edge(int endNode, int value){
        this.endNode = endNode;
        this.value = value;
    }
}