Language: Java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UncheckedIOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Objects;
import java.util.StringTokenizer;

public class D61 {
	public static void main(String[] args) {
		SC sc = new SC(System.in);
		int N=sc.nextInt();
		int M=sc.nextInt();
		long INF=1_000_000_000_000_000L;
		long[] COST=new long[N+1];

		Vertex[] graph=new Vertex[N+1];
		Vertex[] cycle=new Vertex[N+1];
		for(int i=0; i<=N; i++) {
			graph[i]=new Vertex();
			cycle[i]=new Vertex();
			COST[i]=INF;
		}
		for(int i=0; i<M; i++) {
			int from=sc.nextInt();
			int to=sc.nextInt();
			long cost=sc.nextLong();
			graph[from].add(to, cost);
			cycle[from].add(to, -cost);
		}
		COST[0]=0;
		COST[1]=0;
		for(int i=1; i<=N; i++) {
			boolean update=false;
			for(int j=1; j<=M; j++) {
				for(int k=0; k<cycle[j].size(); k++) {
					if(COST[j]!=INF && COST[cycle[j].getKey(k)]>COST[j]+cycle[j].getValue(k)) {
						COST[cycle[j].getKey(k)]=COST[j]+cycle[j].getValue(k);
                        update=true;
					}
				}
			}
			if(update==true) {
				if(i==N) {
					pl("inf");
					System.exit(0);
				}
			}
		}
		Arrays.fill(COST, -INF);
		COST[0]=0;
		COST[1]=0;
		for(int i=1; i<=N; i++) {
			boolean update=false;
			for(int j=1; j<=M; j++) {
				for(int k=0; k<graph[j].size(); k++) {
					if(COST[j]!=-INF && COST[graph[j].getKey(k)]<COST[j]+graph[j].getValue(k)) {
						COST[graph[j].getKey(k)]=COST[j]+graph[j].getValue(k);
						update=true;
					}
				}
			}
			if(update==true) {
				if(i==N) {
					pl("inf");
					System.exit(0);
				}
			}
		}
		pl(COST[N]);
	}
	static class SC {
		private BufferedReader reader = null;
		private StringTokenizer tokenizer = null;
		public SC(InputStream in) {
			reader = new BufferedReader(new InputStreamReader(in));
		}
		public String next() {
			if (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new UncheckedIOException(e);
				}
			}
			return tokenizer.nextToken();
		}
		public int nextInt() {
			return Integer.parseInt(next());
		}
		public long nextLong() {
			return Long.parseLong(next());
		}
		public double nextDouble() {
			return Double.parseDouble(next());
		}
		public String nextLine() {
			try {
				return reader.readLine();
			} catch (IOException e) {
				throw new UncheckedIOException(e);
			}
		}
	}
	public static void pl(Object o) {
		System.out.println(o);
	}
	public static void pl() {
		System.out.println();
	}
	public static void p(Object o) {
		System.out.print(o);
	}
	public static final class Pair<K, V>{        //powered by mikit

		//Pair<任意の型、任意の型>だが、下の機能すべて使うには、Pair<Integer,Long>でないと不可能
		public K key;
		public V value;
		public Pair(K  key, V value) {
			this.key = key;
			this.value = value;
		}
		public static long getValue(Pair<Integer,Long> a) {
			return a.value;
		}
		public static int getKey(Pair<Integer,Long> a) {
			return a.key;
		}
		public boolean equals(Object o) {
			if (this == o) return true;
			if (o == null || getClass() != o.getClass()) return false;
			Pair<?, ?> pair = (Pair<?, ?>) o;
			return Objects.equals(key, pair.key) &&
					Objects.equals(value, pair.value);
		}
		public int hashCode() {
			return Objects.hash(key, value);
		}
	}
	public static class Vertex{
		ArrayList <Pair<Integer,Long>> rinsetu=new ArrayList<Pair<Integer,Long>>();
		public void add(int V,long cost) {
			rinsetu.add(new Pair<Integer, Long>(V,cost));
		}
		public void show() {        //隣接リストを出力
			for(int i=0; i<rinsetu.size(); i++) {
				System.out.println(rinsetu.get(i));
			}
		}
		public void sort_by_cost() {        //コストの低い順にソートします
			rinsetu.sort(Comparator.comparing(p -> p.value));
		}
		public void sort_by_Vertex() {      //向かう頂点の番号順にソートします
			rinsetu.sort(Comparator.comparing(p -> p.key));
		}
		public long getValue(int i) {
			return Pair.getValue(rinsetu.get(i));   //Valueを取り出す
		}
		public Pair<Integer,Long> get(int i) {
			return rinsetu.get(i);   //Pairをぶっこ抜く
		}
		public int getKey(int i) {
			return Pair.getKey(rinsetu.get(i)); //Valueを取り出す
		}
		public void changeKey(int i,int value) {	//リストのペアの前の値（Key,Value）のKeyを書き換え
			Pair<Integer,Long> tmp=new Pair<Integer, Long>(value,Pair.getValue(rinsetu.get(i)));
			rinsetu.set(i, tmp);
		}
		public void changeValue(int i,long value) {	//リストのペアの後ろの値（Key,Value）のValueを書き換え
			Pair<Integer,Long> tmp=new Pair<Integer, Long>(Pair.getKey(rinsetu.get(i)),value);
			rinsetu.set(i, tmp);
		}
		public void changeKeyValue(int i,int key,long value) {	//リストのペアを書き換え（Key,Valueどちらも）
			Pair<Integer,Long> tmp=new Pair<Integer, Long>(key,value);
			rinsetu.set(i, tmp);
		}
		public int size() {     //次数を返す
			return rinsetu.size();
		}
		public int find_Vertex(int a) {     //ある頂点から本当に特定の辺に行くか？  逐次探索なので速さはお察し
			for(int i=0; i<rinsetu.size(); i++) {
				if(a==Pair.getKey(rinsetu.get(i))) {
					return i;
				}
			}
			return -1;
		}
	}
}


Compiler output:
Main.java:12: error: class D61 is public, should be declared in a file named D61.java
public class D61 {
       ^
1 error