Shortest Routes I

Note: input/ShortestRoutesI.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.*;

public class ShortestRoutesI {
    public static void main(String[] args) {
        FastScanner input = new FastScanner(System.in);
        int n = input.nextInt();
        int m = input.nextInt();

        int[][] flightConnections = new int[m][3];

        for (int i = 0; i < m; i++) {
            flightConnections[i][0] = input.nextInt();
            flightConnections[i][1] = input.nextInt();
            flightConnections[i][2] = input.nextInt();
        }

        long[] outputs = new long[n];

        ArrayList<int[]>[] graph = new ArrayList[n];

        for (int i = 0; i < n; i++) {
            graph[i] = new ArrayList<>();
            outputs[i] = Long.MAX_VALUE;
        }

        for (int i = 0; i < m; i++) {
            int from = flightConnections[i][0] - 1;
            int to = flightConnections[i][1] - 1;
            int length = flightConnections[i][2];

            graph[from].add(new int[]{to, length});
        }

        PriorityQueue<long[]> pq =
                new PriorityQueue<>(Comparator.comparingLong(a -> a[1]));

        outputs[0] = 0;
        pq.add(new long[]{0, 0});

        while (!pq.isEmpty()) {
            long[] current = pq.poll();

            int city = (int) current[0];
            long distance = current[1];

            if (distance != outputs[city]) {
                continue;
            }

            for (int[] flight : graph[city]) {
                int nextCity = flight[0];
                long flightLength = flight[1];

                long newDistance = distance + flightLength;

                if (newDistance < outputs[nextCity]) {
                    outputs[nextCity] = newDistance;
                    pq.add(new long[]{nextCity, newDistance});
                }
            }
        }

        for (int i = 0; i < n; i++) {
            System.out.print(outputs[i] + " ");
        }
    }

    static class FastScanner {
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;

    public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    }

    public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

        return tokenizer.nextToken("\n");
    }

    public long nextLong() {
        return Long.parseLong(next());
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }

    public double nextDouble() {
    	 return Double.parseDouble(next());
	 }

    public int[] nextIntArray(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++)
            a[i] = nextInt();
        return a;
    }

    public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    }
}
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED