前往小程序,Get更优阅读体验!
立即前往
首页
学习
活动
专区
工具
TVP
发布
社区首页 >专栏 >1125. Stockbroker Grapevine

1125. Stockbroker Grapevine

作者头像
用户1147447
发布2019-05-26 00:16:14
3370
发布2019-05-26 00:16:14
举报
文章被收录于专栏:机器学习入门

5

POJ 刷题系列:1125. Stockbroker Grapevine

题意:

给出一幅有向图,从某个结点s出发,能够抵到其他任何顶点,且传播到最后一个顶点所需要的时间最短,求s。

思路: 数据很水,用floyd求出任意两点之间的最短距离即可。接着遍历顶点s,求出抵达最后一个顶点的时间t,每个s对应一个t,求出t最小的s。

代码如下:

代码语言:javascript
复制
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Map;
import java.util.StringTokenizer;

public class Main{

    String INPUT = "./data/judge/201712/P1125.txt";

    public static void main(String[] args) throws IOException {
        new Main().run();
    }

    static final int INF = 0x3f3f3f3f;

    int N;
    int[][] dist;

    void read() {
        while (true) {
            N = ni();
            if (N == 0) break;
            dist = new int[N][N];
            for (int i = 0; i < N; ++i) Arrays.fill(dist[i], INF);

            for (int i = 0; i < N; ++i) {
                int M = ni();
                for (int j = 0; j < M; ++j) {
                    int v = ni();
                    int t = ni();
                    v --;
                    dist[i][v] = t;
                }
            }

            // floyd
            for (int k = 0; k < N; ++k) {
                for (int i = 0; i < N; ++i) {
                    for (int j = 0; j < N; ++j) {
                        dist[i][j] = Math.min(dist[i][j], dist[i][k] + dist[k][j]);
                    }
                }
            }

            int min  = INF;
            int minV = -1;

            for (int i = 0; i < N; ++i) {
                boolean valid = true;
                int max = 0;
                for (int j = 0; j < N; ++j) {
                    if (i != j) {
                        if (dist[i][j] == INF) {
                            valid = false;
                            break;
                        }
                        else {
                            max = Math.max(max, dist[i][j]);
                        }
                    }
                }
                if (valid) {
                    if (min > max) {
                        min = max;
                        minV = i;
                    }
                }
            }

            if (minV == -1) out.println("disjoint");
            else {
                out.println((minV + 1) + " " + min);
            }
        }
    }

    FastScanner in;
    PrintWriter out;

    void run() throws IOException {
        boolean oj;
        try {
            oj = ! System.getProperty("user.dir").equals("F:\\oxygen_workspace\\Algorithm");
        } catch (Exception e) {
            oj = System.getProperty("ONLINE_JUDGE") != null;
        }

        InputStream is = oj ? System.in : new FileInputStream(new File(INPUT));
        in = new FastScanner(is);
        out = new PrintWriter(System.out);
        long s = System.currentTimeMillis();
        read();
        out.flush();
        if (!oj){
            System.out.println("[" + (System.currentTimeMillis() - s) + "ms]");
        }
    }

    public boolean more(){
        return in.hasNext();
    }

    public int ni(){
        return in.nextInt();
    }

    public long nl(){
        return in.nextLong();
    }

    public double nd(){
        return in.nextDouble();
    }

    public String ns(){
        return in.nextString();
    }

    public char nc(){
        return in.nextChar();
    }

    class FastScanner {
        BufferedReader br;
        StringTokenizer st;
        boolean hasNext;

        public FastScanner(InputStream is) throws IOException {
            br = new BufferedReader(new InputStreamReader(is));
            hasNext = true;
        }

        public String nextToken() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (Exception e) {
                    hasNext = false;
                    return "##";
                }
            }
            return st.nextToken();
        }

        String next = null;
        public boolean hasNext(){
            next = nextToken();
            return hasNext;
        }

        public int nextInt() {
            if (next == null){
                hasNext();
            }
            String more = next;
            next = null;
            return Integer.parseInt(more);
        }

        public long nextLong() {
            if (next == null){
                hasNext();
            }
            String more = next;
            next = null;
            return Long.parseLong(more);
        }

        public double nextDouble() {
            if (next == null){
                hasNext();
            }
            String more = next;
            next = null;
            return Double.parseDouble(more);
        }

        public String nextString(){
            if (next == null){
                hasNext();
            }
            String more = next;
            next = null;
            return more;
        }

        public char nextChar(){
            if (next == null){
                hasNext();
            }
            String more = next;
            next = null;
            return more.charAt(0);
        }
    }

    static class D{

        public static void pp(int[][] board, int row, int col) {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < row; ++i) {
                for (int j = 0; j < col; ++j) {
                    sb.append(board[i][j] + (j + 1 == col ? "\n" : " "));
                }
            }
            System.out.println(sb.toString());
        }

        public static void pp(char[][] board, int row, int col) {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < row; ++i) {
                for (int j = 0; j < col; ++j) {
                    sb.append(board[i][j] + (j + 1 == col ? "\n" : " "));
                }
            }
            System.out.println(sb.toString());
        }
    }

    static class ArrayUtils {

        public static void fill(int[][] f, int value) {
            for (int i = 0; i < f.length; ++i) {
                Arrays.fill(f[i], value);
            }
        }

        public static void fill(int[][][] f, int value) {
            for (int i = 0; i < f.length; ++i) {
                fill(f[i], value);
            }
        }

        public static void fill(int[][][][] f, int value) {
            for (int i = 0; i < f.length; ++i) {
                fill(f[i], value);
            }
        }
    }

    static class Num{
        public static <K> void inc(Map<K, Integer> mem, K k) {
            if (!mem.containsKey(k)) mem.put(k, 0);
            mem.put(k, mem.get(k) + 1);
        }
    }
}
这里写图片描述
这里写图片描述
本文参与 腾讯云自媒体同步曝光计划,分享自作者个人站点/博客。
原始发表:2017年12月27日,如有侵权请联系 cloudcommunity@tencent.com 删除

本文分享自 作者个人站点/博客 前往查看

如有侵权,请联系 cloudcommunity@tencent.com 删除。

本文参与 腾讯云自媒体同步曝光计划  ,欢迎热爱写作的你一起参与!

评论
登录后参与评论
0 条评论
热度
最新
推荐阅读
目录
  • POJ 刷题系列:1125. Stockbroker Grapevine
领券
问题归档专栏文章快讯文章归档关键词归档开发者手册归档开发者手册 Section 归档