acm 1125 最短路径（floyd）

Description

Stockbrokers are known to overreact to rumours. You have been contracted to develop a method of spreading disinformation amongst the stockbrokers to give your employer the tactical edge in the stock market. For maximum effect, you have to spread the rumours in the fastest possible way.

Unfortunately for you, stockbrokers only trust information coming from their "Trusted sources" This means you have to take into account the structure of their contacts when starting a rumour. It takes a certain amount of time for a specific stockbroker to pass the rumour on to each of his colleagues. Your task will be to write a program that tells you which stockbroker to choose as your starting point for the rumour, as well as the time it will take for the rumour to spread throughout the stockbroker community. This duration is measured as the time needed for the last person to receive the information.

Input

Your program will input data for different sets of stockbrokers. Each set starts with a line with the number of stockbrokers. Following this is a line for each stockbroker which contains the number of people who they have contact with, who these people are, and the time taken for them to pass the message to each person. The format of each stockbroker line is as follows: The line starts with the number of contacts (n), followed by n pairs of integers, one pair for each contact. Each pair lists first a number referring to the contact (e.g. a '1' means person number one in the set), followed by the time in minutes taken to pass a message to that person. There are no special punctuation symbols or spacing rules.

Each person is numbered 1 through to the number of stockbrokers. The time taken to pass the message on will be between 1 and 10 minutes (inclusive), and the number of contacts will range between 0 and one less than the number of stockbrokers. The number of stockbrokers will range from 1 to 100. The input is terminated by a set of stockbrokers containing 0 (zero) people.

Output

For each set of data, your program must output a single line containing the person who results in the fastest message transmission, and how long before the last person will receive any given message after you give it to this person, measured in integer minutes.
It is possible that your program will receive a network of connections that excludes some persons, i.e. some people may be unreachable. If your program detects such a broken network, simply output the message "disjoint". Note that the time taken to pass the message from person A to person B is not necessarily the same as the time taken to pass it from B to A, if such transmission is possible at all.

Sample Input

32 2 4 3 52 1 2 3 62 1 2 2 253 4 4 2 8 5 31 5 84 1 6 4 10 2 7 5 202 2 5 1 50

Sample Output

3 23 10

Source

Southern African 2001


题目大体意思就是：首先第一行输入有几个点，接下来的几行就是每个点的情况，例如：

32 2 4 3 52 1 2 3 62 1 2 2 2

就是三个点，第二行的2代表有两个点与之相关，1-2的路径是4,1-3的路径是5，之后得类比。直到输入的点数为0时退出。以下代码仅供参考：可以改成c++的，提交ACM的题的时候，还是c++的快，java的总出错。

package com.tset;

import java.util.Scanner;

public class TestFloyd {

    private static int MAX = 999999;

    /**
     * @param args
     * acm 1125
     * num:输入几个点
     * tot:自己和其他的几个点有联系
     * temp[k][input1]=input2:自己和其他几个点的路径长度
     */
    public static void main(String[] args) {

        while(true){
            Scanner sc = new Scanner(System.in);
            int num = sc.nextInt();


            Integer[][] temp = new Integer[101][101];
            if(num!=0){
                for(int i=1;i<=num;i++){
                    for(int j=1;j<=num;j++){
                        if(i==j){
                            temp[i][j]=0;
                        } else {
                            temp[i][j]=MAX;
                        }
                    }
                }
                for(int k=1;k<=num;k++){
                    int tot =sc.nextInt();
                    for(int m=1;m<=tot;m++){
                        int input1=sc.nextInt();
                        int input2=sc.nextInt();
                        //设置到其他几个点的路径的长度
                        temp[k][input1]=input2;

                    }

                }
                floyd(num,temp);
            } else {
                break;
            }
            
        }

    }
    /**
     * @param num,temp
     */
    public static void floyd(int num,Integer[][] temp){

        //求两点之间最短的路径
        for(int i=1;i<=num;i++){

            for(int j=1;j<=num;j++){

                for(int k=1;k<=num;k++){

                    if((temp[j][i]+temp[i][k])<temp[j][k])

                        temp[j][k]=temp[j][i]+temp[i][k];
                }
            }
        }
        //最短路径的点
        int minnum = 0;
        //最短路径长度
        int min = MAX;
        for(int m=1;m<=num;m++){
            int maxtemp=0;
            for(int n=1;n<=num;n++){

                if(m==n)
                    continue;
                //求从m出发到其余各点的最大值
                if(temp[m][n]>maxtemp)
                    maxtemp=temp[m][n];
            }

            //记录最短长度
            if(maxtemp<min)
            {
                min=maxtemp;
                minnum=m;
            }
        }

        if(min==MAX){
            System.out.println("disjoint");
        } else{
            System.out.println(minnum+" "+min);
        }
    }


}