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82 lines
2.2 KiB
82 lines
2.2 KiB
# Python program for Dijkstra's single
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# source shortest path algorithm. The program is
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# for adjacency matrix representation of the graph
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# Library for INT_MAX
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import sys
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class Graph():
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def __init__(self, vertices):
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self.V = vertices
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self.graph = [[0 for column in range(vertices)]
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for row in range(vertices)]
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def printSolution(self, dist):
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print "Vertex tDistance from Source"
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for node in range(self.V):
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print node, "t", dist[node]
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# A utility function to find the vertex with
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# minimum distance value, from the set of vertices
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# not yet included in shortest path tree
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def minDistance(self, dist, sptSet):
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# Initilaize minimum distance for next node
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min = sys.maxint
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# Search not nearest vertex not in the
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# shortest path tree
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for v in range(self.V):
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if dist[v] < min and sptSet[v] == False:
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min = dist[v]
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min_index = v
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return min_index
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# Funtion that implements Dijkstra's single source
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# shortest path algorithm for a graph represented
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# using adjacency matrix representation
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def dijkstra(self, src):
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dist = [sys.maxint] * self.V
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dist[src] = 0
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sptSet = [False] * self.V
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for cout in range(self.V):
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# Pick the minimum distance vertex from
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# the set of vertices not yet processed.
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# u is always equal to src in first iteration
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u = self.minDistance(dist, sptSet)
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# Put the minimum distance vertex in the
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# shotest path tree
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sptSet[u] = True
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# Update dist value of the adjacent vertices
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# of the picked vertex only if the current
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# distance is greater than new distance and
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# the vertex in not in the shotest path tree
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for v in range(self.V):
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if self.graph[u][v] > 0 and sptSet[v] == False and \
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dist[v] > dist[u] + self.graph[u][v]:
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dist[v] = dist[u] + self.graph[u][v]
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self.printSolution(dist)
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# Driver program
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g = Graph(9)
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g.graph = [[0, 4, 0, 0, 0, 0, 0, 8, 0],
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[4, 0, 8, 0, 0, 0, 0, 11, 0],
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[0, 8, 0, 7, 0, 4, 0, 0, 2],
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[0, 0, 7, 0, 9, 14, 0, 0, 0],
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[0, 0, 0, 9, 0, 10, 0, 0, 0],
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[0, 0, 4, 14, 10, 0, 2, 0, 0],
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[0, 0, 0, 0, 0, 2, 0, 1, 6],
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[8, 11, 0, 0, 0, 0, 1, 0, 7],
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[0, 0, 2, 0, 0, 0, 6, 7, 0]
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];
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g.dijkstra(0);
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