dijkstra/dijkstra.rb at master · thinkphp/dijkstra · GitHub

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
class Dijkstra

      def initialize(filename, startpoint, endpoint)

         #start node
         @start = startpoint

         #end node
         @end = endpoint

         #in this vector we will hold the shortest path
         @path = []

         #PInfinit
         @PInfinit = 88

         #read and init the father array, selected array and road array
         readAndInit(filename)

         #Dijkstra's algorithm in action and good luck
         dijkstra()

      end

      # This method determines the minimum cost of the shortest path
      def getCost()
          @R[@end]
      end

      # get the shortest path
      def getShortestPath()
          ROAD(@end)
          @path
      end

      def ROAD(node)
          if @F[node] != 0
             ROAD(@F[node])
          end

          @path.push(node)
      end

      def dijkstra()

          start = @start
          min = @PInfinit
          posMin = @PInfinit

          (1..@nodes-1).each do |i|
              @R[i] = @road[start][i]
              if i != start
                 if @R[i] < @PInfinit
                    @F[i] = start
                 end
              end
          end

          #for debug
          #print @R

          @S[start] = 1

          #for debug
          #print @S

          (1..@nodes-2).each do |d|

              min = @PInfinit

              (1..@nodes-1).each do |i|
                  if @S[i] == 0
                     if @R[i] < min
                         min = @R[i]
                         posMin = i
                     end
                  end
              end

              @S[posMin] = 1

              (1..@nodes-1).each do|j|
                  if @S[j] == 0
                           if @R[j] > @R[posMin] + @road[posMin][j]
                              @R[j] = @R[posMin] + @road[posMin][j]
                              @F[j] = posMin
                           end
                  end
              end

          end

      end

      def readAndInit(file)

          arr = []

          File.open(file, "r").each_line { |line| arr << line.split(' ').map {|c| c.to_i} }

          @nodes = arr[0][0] + 1

          n = arr.size()-1

          @road = Array.new(@nodes) { Array.new(@nodes) }
          @R = Array.new(@nodes)
          @S = Array.new(@nodes)
          @F = Array.new(@nodes)

          (0..@nodes-1).each do |i|
              @R[i] = 0
          end

          (0..@nodes-1).each do |i|
              @S[i] = 0
          end

          (0..@nodes-1).each do |i|
              @F[i] = 0
          end

          (0..@nodes-1).each do |i|
              (0..@nodes-1).each do |j|
                  if i == j
                     @road[i][j] = 0
                  else
                     @road[i][j] = @PInfinit
                  end
              end
           end

           (1..n).each do |i|
                  x = arr[i][0]
                  y = arr[i][1]
                  c = arr[i][2]
                  @road[x][y] = c
           end

      end
end

start_point = 1
end_point = 3

ob = Dijkstra.new('dijkstra.in', start_point, end_point)

print "Cost = ", ob.getCost(), "\n"
print "Shortest Path = ", ob.getShortestPath()