1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
#include <stdio.h>
#include <stdlib.h>
#include "graph.h"
typedef struct list_item {
vertex_t *v;
struct list_item *next;
struct list_item *prev;
} list_item_t;
typedef struct {
int len;
struct list_item *begin;
struct list_item *end;
} list_t;
void list_push(list_t *s, vertex_t *v)
{
// Create
list_item_t *i = malloc(sizeof(list_item_t));
i->next = NULL;
i->prev = NULL;
i->v = v;
// Link
if (s->len == 0) {
s->begin = i;
} else {
s->end->next = i;
i->prev = s->end;
}
s->end = i;
s->len++;
}
vertex_t *list_pop_smallest(list_t *s)
{
list_item_t *smallest = s->begin;
// Search
list_item_t *i = s->begin;
while (i) {
if (i->v->dist != -1 && i->v->dist < smallest->v->dist) {
smallest = i;
}
i = i->next;
}
if (smallest == s->begin) {
s->begin = smallest->next;
} else {
smallest->prev->next = smallest->next;
}
if (smallest == s->end) {
s->end = smallest->prev;
} else {
smallest->next->prev = smallest->prev;
}
vertex_t *v = smallest->v;
free(smallest);
s->len--;
return v;
}
graph_t g;
// Assumes u has an edge to v
void relax(vertex_t *u, vertex_t *v)
{
// Get edge between these two guys
edge_t *e = u->adj;
while (e && e->next && e->to->ref != v->ref) {
e = e->next;
}
if (v->dist == -1 || v->dist > (u->dist + e->weight)) {
v->dist = u->dist + e->weight;
v->p = u;
}
}
void dijkstra(graph_t *g, vertex_t *s)
{
list_t list;
list.len = 0;
list.end = list.begin = 0;
s->dist = 0;
{
vertex_t *v = vertex_next(g, NULL);
while (v) {
list_push(&list, v);
v = vertex_next(g, v);
}
}
while (list.len) {
vertex_t *u = list_pop_smallest(&list);
edge_t *e = u->adj;
while (e) {
relax(u, e->to);
e = e->next;
}
}
}
int main()
{
graph_edge(&g, 'a', 'b', 2);
graph_edge(&g, 'a', 'f', 1);
graph_edge(&g, 'b', 'd', 3);
graph_edge(&g, 'b', 'c', 4);
graph_edge(&g, 'd', 'b', 1);
graph_edge(&g, 'd', 'e', 8);
graph_edge(&g, 'c', 'a', 7);
graph_edge(&g, 'c', 'd', 7);
graph_edge(&g, 'c', 'f', 2);
graph_edge(&g, 'e', 'c', 2);
graph_edge(&g, 'e', 'f', 2);
dijkstra(&g, g.vertexes['a']);
graph_to_dot(stdout, &g);
return 0;
}
|
