Submission #119687

#	Time	Username	Problem	Language	Result	Execution time	Memory
119687		DS007	Jakarta Skyscrapers (APIO15_skyscraper)	Java	0 / 100	88 ms	9892 KiB

skyscraper

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

class Codechef {

    static class Reader
    {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader()
        {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException
        {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException
        {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1)
            {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do
            {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException
        {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException
        {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();

            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');

            if (c == '.')
            {
                while ((c = read()) >= '0' && c <= '9')
                {
                    ret += (c - '0') / (div *= 10);
                }
            }

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException
        {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException
        {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException
        {
            if (din == null)
                return;
            din.close();
        }
    }

    static class Node {
        int vertex, dist;

        Node(int a, int b) {
            vertex = a;
            dist = b;
        }

        int getDist() {
            return dist;
        }
    }

    static class Graph {

        LinkedList<Node> adj[];
        int n;
        int distance[];
        HashSet<Integer> settled;
        PriorityQueue<Node> pq;

        Graph(int n) {
            this.n = n;
            adj = new LinkedList[n];
            distance = new int[n];
            Arrays.fill(distance, Integer.MAX_VALUE);
            settled = new HashSet<>(n);
            pq = new PriorityQueue<>(Comparator.comparing(Node::getDist));
            for (int i = 0; i < n; i++)
                adj[i] = new LinkedList<>();
        }

        void addEdge(int a, int b, int dist) {
            adj[a].add(new Node(b, dist));
        }

        int solve(int u, int v) {
            distance[u] = 0;
            pq.add(new Node(u, 0));

            while (pq.size() != 0 && settled.size() != n && !settled.contains(v)) {
                int p = pq.remove().vertex;
                settled.add(p);
                check_neighbours(p);
            }

            if (distance[v] == Integer.MAX_VALUE)
                return -1;
            else
                return distance[v];
        }

        void check_neighbours(int v) {
            for (Node i : adj[v]) {
                if (!settled.contains(i.vertex)) {
                    int newDist = distance[v] + i.dist;
                    distance[i.vertex] = Math.min(distance[i.vertex], newDist);
                    pq.add(new Node(i.vertex, distance[i.vertex]));
                }
            }
        }
    }

    public static void main(String args[]) throws Exception {

        Reader r = new Reader();
        int n = r.nextInt(), m = r.nextInt(), p0 = -1, p1 = -1;
        Graph g = new Graph(n);

        for (int i = 0; i < m; i++) {
            int b = r.nextInt(), p = r.nextInt();
            if (i == 0)
                p0 = b;
            if (i == 1)
                p1 = b;
            for (int j = b + p, k = 1; j < n; j += p, k++)
                g.addEdge(b, j, k);
            for (int j = b - p, k = 1; j >= 0; j -= p, k++)
                g.addEdge(b, j, k);
        }

        System.out.print(g.solve(p0, p1));
    }
}

Compilation message (stderr)

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

• Subtask 1: 0 / 10
• Subtask 2: 0 / 12
• Subtask 3: 0 / 14
• Subtask 4: 0 / 21
• Subtask 5: 0 / 43