제출 #489792

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
489792		rainliofficial	Robot (JOI21_ho_t4)	Java	0 / 100	3082 ms	511420 KiB

Main

import java.io.*;
import java.util.*;

public class Main {
    static int n, m;
    static ArrayList<Edge>[] arr;
    static HashMap<Integer, Long>[] dist;
    //static HashMap<Integer, ArrayList<Edge>>[] arr;
    static HashMap<Integer, Integer>[] recolor; // Stores the cost to recolor all edges of a certain color at a node

    public static void main(String[] args) throws IOException{
        BufferedReader file = new BufferedReader(new InputStreamReader(System.in));
        //BufferedReader file = new BufferedReader(new FileReader("file.in"));
        // PrintWriter outfile = new PrintWriter (new BufferedWriter(new FileWriter("Robot.out")));
        StringTokenizer st = new StringTokenizer(file.readLine());
        n = Integer.parseInt(st.nextToken());
        m = Integer.parseInt(st.nextToken());
        //arr = new HashMap[n];
        arr = new ArrayList[n];
        recolor = new HashMap[n];
        dist = new HashMap[n];
        recolor  = new HashMap[n];
        for (int i=0; i<n; i++){
            arr[i] = new ArrayList<>();
            recolor[i] = new HashMap<>();
            dist[i] = new HashMap<>();
            recolor[i] = new HashMap<>();
        }
        for (int i=0; i<m; i++){
            st = new StringTokenizer(file.readLine());
            int s = Integer.parseInt(st.nextToken())-1;
            int e = Integer.parseInt(st.nextToken())-1;
            int color = Integer.parseInt(st.nextToken());
            int cost = Integer.parseInt(st.nextToken());
            arr[s].add(new Edge(e, color, cost, i));
            arr[e].add(new Edge(s, color, cost, i));
            addEdge(s, e, color, cost);
            addEdge(e, s, color, cost);
        }
        // Do Dijkstra on expanded states. State = current node, the original color of the edge we just walked through,
        // (if we recolored it). Total N+M states. 
        PriorityQueue<State> pq = new PriorityQueue<>();
        pq.add(new State(0, -1, 0, 0, -1));
        while (!pq.isEmpty()){
            State curr = pq.poll();
            if (dist[curr.node].containsKey(curr.prevColor) && dist[curr.node].get(curr.prevColor) != curr.cost){
                continue; 
            }
            for (Edge e : arr[curr.node]){
                if (!recolor[curr.node].containsKey(e.color) || e.id == curr.prevEdgeId){
                    continue;
                }
                long nc = curr.cost + recolor[curr.node].get(e.color) - e.cost;
                if (curr.prevColor == e.color){
                    nc -= curr.prevEdgeCost;
                }
                addState(pq, e.to, -1, nc, e.cost, e.id);
                addState(pq, e.to, e.cost, curr.cost + e.cost, e.cost, e.id);
            }
        }
        long ans = Long.MAX_VALUE;
        for (int c : dist[n-1].keySet()){
            ans = Math.min(dist[n-1].get(c), ans);
        }
        if (ans == Long.MAX_VALUE) ans = -1;
        System.out.println(ans);
    }
    public static void addEdge(int ind, int to, int color, int cost){
        if (!recolor[ind].containsKey(color)){
            // arr[ind].put(color, new ArrayList<>());
            recolor[ind].put(color, 0);
        }
        // arr[ind].get(color).add(new Edge(to, color, cost));
        recolor[ind].put(color, recolor[ind].get(color) + cost);
    }
    public static void addState(PriorityQueue<State> pq, int ind, int prevColor, long newDist, int prevEdgeCost, int id){ // Return true if element added, or false if not added
        if (!dist[ind].containsKey(prevColor) || dist[ind].get(prevColor) > newDist){
            dist[ind].put(prevColor, newDist);
            pq.add(new State(ind, prevColor, newDist, prevEdgeCost, id));
        }
    }
    static class State implements Comparable<State>{
        int node, prevColor, prevEdgeCost, prevEdgeId;
        long cost;
        public State(int node, int prevColor, long cost, int prevEdgeCost, int prevEdgeId){
            this.node = node;
            this.prevColor = prevColor;
            this.cost = cost;
            this.prevEdgeCost = prevEdgeCost;
            this.prevEdgeId = prevEdgeId;
        }
        public int compareTo(State o){
            return Long.compare(this.cost, o.cost);
        }
    }
    static class Edge{
        int to, color, cost, id;
        public Edge(int to, int color, int cost, int id){
            this.to = to;
            this.color = color;
            this.cost = cost;
            this.id = id;
        }
    }
}

컴파일 시 표준 에러 (stderr) 메시지

Note: Main.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

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