54 lines
977 B
Python
54 lines
977 B
Python
A = "A"
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B = "B"
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C = "C"
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#D = "D"
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E = "E"
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F = "F"
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nodes = [A,B,C,E,F]
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edges = {
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(A,B,3),
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(A,C,4),
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# (B,D,5),
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(B,E,2),
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# (C,D,1),
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# (D,E,2),
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# (D,F,4),
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(E,F,6)
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}
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def getadjacent(node, edges):
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adjacent = set()
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for (s,t,l) in edges:
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if s == node:
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adjacent.add( (t,l) )
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elif t == node:
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adjacent.add( (s,l) )
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return adjacent
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def spr(s,t, nodes, edges):
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nodes = set(nodes)
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m = { s:(0,[s])}
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S = set([s])
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S2 = set(S)
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while S < nodes:
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for s in set(S2):
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S2.remove( s )
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l,p = m[s]
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for (ad,sl) in getadjacent(s, edges):
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if ad not in S:
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m[ad] = (l+sl,p+[ad])
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else:
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ad_l,_ = m[ad]
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if ad_l > l+sl:
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m[ad] = (l+sl,p+[ad])
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S.add( ad )
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S2.add( ad )
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return m[t]
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print( spr(A,F, nodes, edges) )
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