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55 lines
1.2 KiB
Python
55 lines
1.2 KiB
Python
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from __future__ import print_function
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def printDist(dist, V):
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print("\nVertex Distance")
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for i in range(V):
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if dist[i] != float('inf') :
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print(i,"\t",int(dist[i]),end = "\t")
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else:
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print(i,"\t","INF",end="\t")
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print()
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def BellmanFord(graph, V, E, src):
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mdist=[float('inf') for i in range(V)]
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mdist[src] = 0.0
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for i in range(V-1):
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for j in range(V):
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u = graph[j]["src"]
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v = graph[j]["dst"]
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w = graph[j]["weight"]
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if mdist[u] != float('inf') and mdist[u] + w < mdist[v]:
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mdist[v] = mdist[u] + w
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for j in range(V):
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u = graph[j]["src"]
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v = graph[j]["dst"]
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w = graph[j]["weight"]
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if mdist[u] != float('inf') and mdist[u] + w < mdist[v]:
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print("Negative cycle found. Solution not possible.")
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return
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printDist(mdist, V)
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#MAIN
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V = int(raw_input("Enter number of vertices: "))
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E = int(raw_input("Enter number of edges: "))
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graph = [dict() for j in range(E)]
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for i in range(V):
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graph[i][i] = 0.0
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for i in range(E):
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print("\nEdge ",i+1)
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src = int(raw_input("Enter source:"))
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dst = int(raw_input("Enter destination:"))
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weight = float(raw_input("Enter weight:"))
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graph[i] = {"src": src,"dst": dst, "weight": weight}
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gsrc = int(raw_input("\nEnter shortest path source:"))
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BellmanFord(graph, V, E, gsrc)
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