-
ROBERT SEDGEWICK | KEVIN WAYNE
F O U R T H E D I T I O N
Algorithms
http://algs4.cs.princeton.edu
Algorithms ROBERT SEDGEWICK | KEVIN WAYNE
BELLMAN-FORD DEMO
http://algs4.cs.princeton.eduhttp://algs4.cs.princeton.eduhttp://algs4.cs.princeton.eduhttp://algs4.cs.princeton.edu
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
2
0
4
7
1 3
5
2
6
s
69
8
4
5
7
1
54
15
312
20
13
11
9
an edge-weighted digraph
0→1 5.0
0→4 9.0
0→7 8.0
1→2 12.0
1→3 15.0
1→7 4.0
2→3 3.0
2→6 11.0
3→6 9.0
4→5 4.0
4→6 20.0
4→7 5.0
5→2 1.0
5→6 13.0
7→5 6.0
7→2 7.0
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
3
4
7
1 3
5
2
6
initialize
0
v distTo[] edgeTo[]
0 0.0 -
1
2
3
4
5
6
7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
4
4
7
1 3
5
2
6
pass 0
0
0 5
∞
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
distTo[1]
distTo[0] v distTo[] edgeTo[]
0 0.0 -
1
2
3
4
5
6
7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
5
4
7
1 3
5
2
6
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
0
0 5
∞ 5
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2
3
4
5
6
7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
6
4
7
1 3
5
2
6
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
0
0
∞
9
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2
3
4
5
6
7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
7
4
7
1 3
5
2
6
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
0
0
∞ 9
9
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2
3
4 9.0 0→4
5
6
7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
8
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
0
∞8
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2
3
4 9.0 0→4
5
6
7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
9
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
0
∞ 88
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2
3
4 9.0 0→4
5
6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
10
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2
3
4 9.0 0→4
5
6
7 8.0 0→7
∞
5
12
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
11
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
∞
5
12
17
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3
4 9.0 0→4
5
6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
12
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
∞
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3
4 9.0 0→4
5
6
7 8.0 0→7
5
15
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
13
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
∞515
20
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5
6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
14
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
5
8
4
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5
6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
15
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
17
20
3
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5
6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
16
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5
6
7 8.0 0→7
17
∞
11
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
17
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
17
∞ 28
11
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5
6 28.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
18
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
20
28
9
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5
6 28.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
19
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5
6 28.0 2→6
7 8.0 0→7
9
∞4
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
20
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
9
∞ 134
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 28.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
21
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
9 28
20
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 28.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
22
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
9
8
5
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 28.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
23
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 17.0 1→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 28.0 2→6
7 8.0 0→7
17
13
1
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
24
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
17
13
1
14
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 28.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
25
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 28.0 2→6
7 8.0 0→7
28
13 13
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
26
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
28
13 13
26
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
27
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
8
13
6
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
28
4
7
1 3
5
2
6
0
pass 0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
8
147
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
29
4
7
1 3
5
2
6
pass 1
0
0 5
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
5
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
30
4
7
1 3
5
2
6
pass 1
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
0
0
9
9
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
31
4
7
1 3
5
2
6
0
pass 1
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
0
8 8
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
32
4
7
1 3
5
2
6
0
pass 1
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
5
12
14
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
33
4
7
1 3
5
2
6
0
pass 1
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
5
15
20
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
34
4
7
1 3
5
2
6
0
pass 1
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
5
8
4
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
35
4
7
1 3
5
2
6
0
pass 1
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
14
20
3
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 20.0 1→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
36
4
7
1 3
5
2
6
0
pass 1
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
14
20
3
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
17
2-3 successfully relaxedin pass 1, but not pass 0
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
37
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
14
11
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 26.0 5→6
7 8.0 0→7
26
pass 1
-
Repeat V times: relax all E edges.
26
Bellman-Ford algorithm demo
38
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
14
25
11
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
2-6 successfully relaxedin pass 0 and pass 1
pass 1
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
39
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
17
9
25
pass 1
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
40
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
9
4
pass 1
13
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
41
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
9 25
20
pass 1
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
42
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
9
8
5
pass 1
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
43
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
14
13
1
pass 1
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
44
4
7
1 3
5
2
6
0
pass 1
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
25
13 13
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
45
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
8
13
6
pass 1
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
46
4
7
1 3
5
2
6
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
8
147
pass 1
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
47
4
7
1 3
5
2
6
pass 2, 3, 4, 5, 6, 7 (no further changes)
0
0→1 0→4 0→7 1→2 1→3 1→7 2→3 2→6 3→6 4→5 4→6 4→7 5→2 5→6 7→5
7→2
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
-
Repeat V times: relax all E edges.
Bellman-Ford algorithm demo
48
0
4
7
1
5
2
6
v distTo[] edgeTo[]
0 0.0 -
1 5.0 0→1
2 14.0 5→2
3 17.0 2→3
4 9.0 0→4
5 13.0 4→5
6 25.0 2→6
7 8.0 0→7
3
shortest-paths tree from vertex s
s
![A Potential-Based Variant of the Bellman-Ford …ceur-ws.org/Vol-2504/paper15.pdfThe Bellman-Ford algorithm [Bel58,For56] maintains a FIFO queue of la-beled nodes. A node that becomes](https://img.pdfslide.us/doc/110x75/5e73c240896a6715033aba0e/a-potential-based-variant-of-the-bellman-ford-ceur-wsorgvol-2504-the-bellman-ford.jpg)
![4.4 BELLMAN-FORD DEMOxiaojuan/algo16/slides/7DemoBellmanFor… · Repeat V times: relax all E edges. Bellman-Ford algorithm demo 3 4 7 1 3 5 2 6 initialize 0 v distTo[] edgeTo[] 0](https://img.pdfslide.us/doc/110x75/600ad23c9473ea2d4c6d5ff8/44-bellman-ford-demo-xiaojuanalgo16slides7demobellmanfor-repeat-v-times-relax.jpg)
