-
Notifications
You must be signed in to change notification settings - Fork 0
/
dijkstra.hpp
199 lines (165 loc) · 5.46 KB
/
dijkstra.hpp
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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
#pragma once
#include "Graph.hpp"
#include <functional>
#include <limits>
#include <limits.h>
#include <optional>
#include <algorithm>
template<typename V, typename E>
std::pair<double, std::vector<std::size_t>> dijkstra(Graph<V, E>& graph, std::size_t start_idx, std::size_t end_idx,
std::function<double(const E&)> getEdgeLength =
[](const E&edge)->double{return edge;})
{
constexpr double MAX_DOUBLE_VALUE = std::numeric_limits<double>::max();
const std::size_t verticesNumber = graph.nrOfVertices();
if(start_idx>=verticesNumber|| end_idx>=verticesNumber)
{
std::size_t var1 = std::max(start_idx,end_idx);
throw std::runtime_error("[Dijikstra algorithm] Incorrect vertex index: "
+std::to_string(var1));
}
class DijikstraNode
{
public:
DijikstraNode()
:visited(false),distance(MAX_DOUBLE_VALUE)
{
}
bool visited;
double distance;
std::optional<std::size_t > precursor;
};
std::vector<DijikstraNode> nodes(verticesNumber);
nodes[start_idx].distance = 0;
std::size_t currentVertex = start_idx;
while(true)
{
if(currentVertex == end_idx)break;
else if(currentVertex >= verticesNumber)
{
return std::make_pair(MAX_DOUBLE_VALUE,std::vector<std::size_t>());
}
nodes[currentVertex].visited = true;
std::size_t nextVertex = verticesNumber;
double var1 = MAX_DOUBLE_VALUE;
for(std::size_t i=0;i<verticesNumber;++i)
{
if(!nodes[i].visited)
{
if(graph.edgeExist(currentVertex,i))
{
double newDistance = nodes[currentVertex].distance +
getEdgeLength(graph.edgeLabel(currentVertex,i));
if(newDistance < nodes[i].distance)
{
nodes[i].distance = newDistance;
nodes[i].precursor = currentVertex;
}
}
if(nodes[i].distance < var1)
{
var1 = nodes[i].distance;
nextVertex = i;
}
}
}
currentVertex = nextVertex;
}
std::vector<std::size_t> result;
currentVertex = end_idx;
do
{
result.push_back(currentVertex);
if(nodes[currentVertex].precursor.has_value())
{
currentVertex = nodes[currentVertex].precursor.value();
}
else
{
return std::make_pair(MAX_DOUBLE_VALUE,std::vector<std::size_t>());
}
}while(currentVertex!=start_idx);
result.push_back(start_idx);
std::reverse(result.begin(),result.end());
return std::make_pair(nodes[end_idx].distance,result);
}
template<typename V,typename E>
std::vector<std::size_t> dijkstra_old(Graph<V,E>&g,
std::size_t begin,
std::size_t end,
const std::function<std::size_t(const E&)>metric
= [](const E&edge)->unsigned int{return edge;})
{
const std::size_t verticesNumber = g.nrOfVertices();
if(begin>=verticesNumber|| end>=verticesNumber)
{
std::size_t var1 = std::max(begin,end);
throw std::runtime_error("[Dijikstra algorithm] Incorrect vertex index: "
+std::to_string(var1));
}
class DijikstraNode
{
public:
DijikstraNode()
:visited(false),distance(UINT_MAX)
{
}
bool visited;
unsigned int distance;
std::optional<std::size_t > precursor;
};
std::vector<DijikstraNode> nodes(verticesNumber);
nodes[begin].distance = 0;
std::size_t currentVertex = begin;
while(true)
{
if(currentVertex == end)break;
else if(currentVertex >= verticesNumber)
{
std::cout<<"[Dijikstra] No path exists."<<std::endl;
return std::vector<std::size_t>();
}
nodes[currentVertex].visited = true;
std::size_t nextVertex = verticesNumber;
unsigned int var1 = UINT_MAX;
for(std::size_t i=0;i<verticesNumber;++i)
{
if(!nodes[i].visited)
{
if(g.edgeExist(currentVertex,i))
{
unsigned int newDistance = nodes[currentVertex].distance +
metric(g.edgeLabel(currentVertex,i));
if(newDistance < nodes[i].distance)
{
nodes[i].distance = newDistance;
nodes[i].precursor = currentVertex;
}
}
if(nodes[i].distance < var1)
{
var1 = nodes[i].distance;
nextVertex = i;
}
}
}
currentVertex = nextVertex;
}
std::vector<std::size_t> result;
currentVertex = end;
do
{
result.push_back(currentVertex);
if(nodes[currentVertex].precursor.has_value())
{
currentVertex = nodes[currentVertex].precursor.value();
}
else
{
throw std::runtime_error("[Dijikstra algorithm] Error, no precursor");
}
}while(currentVertex!=begin);
result.push_back(begin);
std::reverse(result.begin(),result.end());
return result;
}