[JAVA-자바] 1753번: 최단경로

 

소스코드:

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.PriorityQueue;
import java.util.StringTokenizer;

public class Main {
    public static class Node {
        int to;
        int cost;

        Node(int t, int c) {
            this.to = t;
            this.cost = c;
        }
    }

    static BufferedReader br;
    static BufferedWriter bw;

    static List<List<Node>> nodeList;
    static int V, E, start;

    public static void main(String[] args) throws IOException {
        br = new BufferedReader(new InputStreamReader(System.in));
        bw = new BufferedWriter(new OutputStreamWriter(System.out));

        StringTokenizer st = new StringTokenizer(br.readLine());
        V = Integer.parseInt(st.nextToken());
        E = Integer.parseInt(st.nextToken());
        start = Integer.parseInt(br.readLine());

        nodeList = new ArrayList<>();
        for (int i = 0; i <= V; i++) {
            nodeList.add(new ArrayList<>());
        }
        for (int i = 0; i < E; i++) {
            st = new StringTokenizer(br.readLine());
            int start = Integer.parseInt(st.nextToken());
            int to = Integer.parseInt(st.nextToken());
            int cost = Integer.parseInt(st.nextToken());
            nodeList.get(start).add(new Node(to, cost));
        }
        br.close();

        int[] from = dijkstra(start, V);
        for (int i = 1; i <= V; i++) {
            int cost = from[i];
            if (cost == Integer.MAX_VALUE) {
                bw.write("INF\n");
            } else {
                bw.write(cost + "\n");
            }
        }
        bw.close();
    }

    public static int[] dijkstra(int start, int to) {
        int[] distance = new int[V + 1];
        Arrays.fill(distance, Integer.MAX_VALUE);

        distance[start] = 0;
        PriorityQueue<Node> pq = new PriorityQueue<>((o1, o2) -> o1.cost - o2.cost);
        pq.add(new Node(start, 0));

        while (!pq.isEmpty()) {
            Node current = pq.poll();

            if (current.cost > distance[current.to]) {
                continue;
            }

            for (Node next : nodeList.get(current.to)) {
                if (distance[next.to] > current.cost + next.cost) {
                    distance[next.to] = current.cost + next.cost;
                    pq.add(new Node(next.to, distance[next.to]));
                }
            }
        }
        return distance;
    }

}

 

글의 내용 중 잘못된 점이나 수정이 필요한 부분, 혹은 궁금한 사항이 있다면 언제든 댓글로 남겨주시면 감사하겠습니다.

여러분의 피드백은 더 나은 글을 작성하는 데 큰 도움이 됩니다. 감사합니다.