最短路 bellman-ford算法

 1 package job525;
 2 
 3 import java.util.Scanner;
 4 
 5 class Eage{
 6     int from;
 7     int to;
 8     int cost;
 9 
10     public int getFrom() {
11         return from;
12     }
13     public void setFrom(int from) {
14         this.from = from;
15     }
16     public int getTo() {
17         return to;
18     }
19     public void setTo(int to) {
20         this.to = to;
21     }
22     public int getCost() {
23         return cost;
24     }
25     public void setCost(int cost) {
26         this.cost = cost;
27     }
28     public Eage(int from,int to,int cost)
29     {
30         this.from = from;
31         this.to = to;
32         this.cost = cost;
33     }
34 }
35 
36 public class 最短路bellman_ford {
37     
38     static int m,n,inf=100000;//n：n个顶点；m：m条边
39     static int []d=new int[20000];
40     static Eage []eg=new Eage[200000];
41     
42     public static void main(String[] args) {
43         Scanner sc=new Scanner(System.in);
44         n=sc.nextInt();m=sc.nextInt();
45         int i=0;
46         while(i<m)
47         {
48             int u, v, l;
49             u=sc.nextInt();
50             v=sc.nextInt();
51             l=sc.nextInt();
52             eg[i++]=new Eage(u,v,l);
53         }
54         //测试存储---------------------------------------------------------------------------------
55         /*
56         for(i=0;i<m;i++)
57         {
58             System.out.println("("+eg[i].getFrom()+","+eg[i].getTo()+"):"+eg[i].getCost());
59         }
60         */
61         //测试结束----------------------------------------------------------------------------------
62         bellman_ford();
63         for(i=2;i<=n;i++)
64         {
65             System.out.println(d[i]);
66         }
67     }
68     public static void bellman_ford()
69     {
70         init();
71         while(true)
72         {
73             boolean flag=false;
74             for(int i=0;i<m;i++)
75             {
76                 Eage e=eg[i];
77                 if(d[e.getFrom()]!=inf&&d[e.getTo()]>d[e.getFrom()]+e.getCost())
78                 {
79                     d[e.getTo()]=d[e.getFrom()]+e.getCost();
80                     //System.out.println("("+eg[i].getFrom()+","+eg[i].getTo()+"):"+eg[i].getCost()+d[e.getTo()]);//测试
81                     flag=true;
82                 }
83             }
84             if(!flag)
85                 break;
86         }
87     }
88     public static void init()
89     {
90         for(int i=1;i<=n;i++)
91             d[i]=inf;
92         d[1]=0;
93     }
94 }