54 lines
1.5 KiB
Python
54 lines
1.5 KiB
Python
def main():
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n, m, k = map(int, input().split())
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a = [int(i) for i in input().split()]
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# roads = [list(map(int, input().split())) for _ in range(m)]
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voisins = {i:set() for i in range(1, n+1)}
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A = set(a) # pour les test d'appartenance
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special = False
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for _ in range(m):
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x, y = map(int, input().split())
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voisins[x].add(y)
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voisins[y].add(x)
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if not special and (x in A and y in A):
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special = True
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def distance(source, dist):
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"""calculer la distance d'un sommet à tous les autres"""
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non_vus = set((i+1 for i in range(n) if i+1 != source))
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queue = [source]
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dist[source] = 0
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while queue != []:
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nextQ = []
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while queue != []:
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s = queue.pop()
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for v in voisins[s]:
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if v in non_vus:
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non_vus.remove(v)
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nextQ.append(v)
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dist[v] = dist[s]+1
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queue = nextQ
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dist_n = [0 for _ in range(n+1)]
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dist_1 = [0 for _ in range(n+1)]
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distance(n, dist_n)
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distance(1, dist_1)
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if special:
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return dist_n[1] # On ne rajoute rien
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# On regarde lequel ajouter
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a.sort(key=lambda x: dist_1[x]-dist_n[x])
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sp_count = len(a)
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b = [dist_n[a[-1]] for i in range(sp_count)]
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for sp in range(1, sp_count):
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b[sp_count-1-sp] = max(b[sp_count-sp], dist_n[a[sp_count-sp]])
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return min(
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dist_1[n],
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max((dist_1[a[i]]+b[i] for i in range(0, len(a)-1)))+1
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)
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print(main()) |