1+ import java .util .*;
2+ import java .lang .*;
3+ import java .io .*;
4+ 5+ public class bellman_ford_algo {
6+ 7+ class Edge {
8+ int src , dest , weight ;
9+ 10+ Edge () {
11+ src = dest = weight = 0 ;
12+ }
13+ }
14+ 15+ private int V , E ;
16+ private Edge [] edge ;
17+ 18+ // Creates a graph with V vertices and E edges
19+ private bellman_ford_algo (int v , int e ) {
20+ V = v ;
21+ E = e ;
22+ edge = new Edge [e ];
23+ for (int i = 0 ; i < e ; ++i )
24+ edge [i ] = new Edge ();
25+ }
26+ 27+ public static void main (String [] args ) {
28+ int V = 5 ;
29+ int E = 8 ;
30+ 31+ bellman_ford_algo graph = new bellman_ford_algo (V , E );
32+ 33+ graph .edge [0 ].src = 0 ;
34+ graph .edge [0 ].dest = 1 ;
35+ graph .edge [0 ].weight = -1 ;
36+ 37+ graph .edge [1 ].src = 0 ;
38+ graph .edge [1 ].dest = 2 ;
39+ graph .edge [1 ].weight = 4 ;
40+ 41+ graph .edge [2 ].src = 1 ;
42+ graph .edge [2 ].dest = 2 ;
43+ graph .edge [2 ].weight = 3 ;
44+ 45+ graph .edge [3 ].src = 1 ;
46+ graph .edge [3 ].dest = 3 ;
47+ graph .edge [3 ].weight = 2 ;
48+ 49+ graph .edge [4 ].src = 1 ;
50+ graph .edge [4 ].dest = 4 ;
51+ graph .edge [4 ].weight = 2 ;
52+ 53+ graph .edge [5 ].src = 3 ;
54+ graph .edge [5 ].dest = 2 ;
55+ graph .edge [5 ].weight = 5 ;
56+ 57+ graph .edge [6 ].src = 3 ;
58+ graph .edge [6 ].dest = 1 ;
59+ graph .edge [6 ].weight = 1 ;
60+ 61+ graph .edge [7 ].src = 4 ;
62+ graph .edge [7 ].dest = 3 ;
63+ graph .edge [7 ].weight = -3 ;
64+ 65+ bellman_ford_algo .BellmanFord (graph , 0 );
66+ }
67+ 68+ private static void BellmanFord (bellman_ford_algo graph , int src ) {
69+ int V = graph .V , E = graph .E ;
70+ int dist [] = new int [V ];
71+ 72+ for (int i = 0 ; i < V ; ++i )
73+ dist [i ] = Integer .MAX_VALUE ;
74+ dist [src ] = 0 ;
75+ 76+ for (int i = 1 ; i < V ; ++i ) {
77+ for (int j = 0 ; j < E ; ++j ) {
78+ int u = graph .edge [j ].src ;
79+ int v = graph .edge [j ].dest ;
80+ int weight = graph .edge [j ].weight ;
81+ if (dist [u ] != Integer .MAX_VALUE && dist [u ] + weight < dist [v ])
82+ dist [v ] = dist [u ] + weight ;
83+ }
84+ }
85+ 86+ for (int j = 0 ; j < E ; ++j ) {
87+ int u = graph .edge [j ].src ;
88+ int v = graph .edge [j ].dest ;
89+ int weight = graph .edge [j ].weight ;
90+ if (dist [u ] != Integer .MAX_VALUE && dist [u ] + weight < dist [v ]) {
91+ System .out .println ("Graph contains negative weight cycle" );
92+ return ;
93+ }
94+ }
95+ printArr (dist , V );
96+ }
97+ 98+ private static void printArr (int [] dist , int V ) {
99+ System .out .println ("Vertex Distance from Source" );
100+ for (int i = 0 ; i < V ; ++i )
101+ System .out .println (i + "\t \t " + dist [i ]);
102+ }
103+ }
0 commit comments