Lennot

import java.util.ArrayList;
import java.util.TreeMap;

public class Lennot{
    
    private static int n;
    private static long[] leastPrices;
    private static boolean[] beenTo;
    private static ArrayList<flight>[] connections;
    private static TreeMap<Long, ArrayList<Integer>> currentNodes;
    
    public static void main(String[] args){
        IO io = new IO();
        
        n = io.nextInt();
        int m = io.nextInt();
        
        beenTo = new boolean[n];
        leastPrices = new long[n];
        connections = new ArrayList[n];
        for(int i = 0; i < n; i++){
            connections[i] = new ArrayList();
            leastPrices[i] = Long.MAX_VALUE;
        }
        
        
        for(int i = 0; i < m; i++){
            int a = io.nextInt() - 1, b = io.nextInt() - 1, h = io.nextInt();
            connections[a].add(new flight(b, h));
        }
        
        currentNodes = new TreeMap();
        currentNodes.put(0l, new ArrayList());
        currentNodes.get(0l).add(0);
        
        ArrayList<Integer> cities;
        
        boolean stop = false;
        long ans = 0;
        while(!stop){
            cities = currentNodes.firstEntry().getValue();
            for(int city: cities){
                
                if(city == n-1){
                    stop = true;
                    ans = currentNodes.firstKey();
                    break;
                }
                
                fly(currentNodes.firstKey(), city);
            }
            
            currentNodes.pollFirstEntry();
        }
        
        io.println(ans);
        io.close();
    }
    
    private static void fly(long price, int city){
        
        if(beenTo[city])
            return;
        
        beenTo[city] = true;
        
        for(flight f: connections[city]){
            
            long newPrice = price + f.price;
            
            if(f.city == n-1){
                ArrayList list = currentNodes.get(newPrice);
                if(list == null){
                    list = new ArrayList();
                    list.add(n-1);
                    currentNodes.put(newPrice, list);
                }else
                    list.add(0, n-1);
            }
            
            for(flight f2: connections[f.city]){
                
                if(leastPrices[f2.city] > newPrice){
                    leastPrices[f2.city] = newPrice;
                    
                    ArrayList list = currentNodes.get(newPrice);
                    if(list == null){
                        list = new ArrayList();
                        list.add(f2.city);
                        currentNodes.put(newPrice, list);
                    }else
                        list.add(f2.city);
                }
            }
        }
    }
    
    private static class flight{
        int city, price;
        
        public flight(int city, int price){
            this.city = city;
            this.price = price;
        }
    }
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED

Test 16

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 17

Group: 3

Verdict: TIME LIMIT EXCEEDED