"cf707b" Bakery (idea title)

Test instructions

There are n cities, m-strips without sides, of which K cities are warehouses

Now choose a bakery in a non-warehouse city, making it a minimum of one warehouse and a minimum for all warehouse distances

(1≤ n, m ≤10^5, 0≤ k ≤ n)

Analysis:

The data range determines the solution using only O (n) or O (n log n)

After thinking, you can find that the bakery must be selected in a city directly connected to a warehouse.

Otherwise, it will be through another indirectly connected to the city to go, a few more roads

1 varA,b,c,flag:Array[1..100000] ofLongint;2 N,m,k,i,ans,x:longint;3 4 begin5 readln (n,m,k);6   fori:=1  toM Doreadln (A[i],b[i],c[i]);7   fori:=1  toK Do8  begin9 read (x);Tenflag[x]:=1; One  End; Aans:=Maxlongint; -   fori:=1  toM Do -   ifflag[a[i]]+flag[b[i]]=1  Then the    ifC[i]<ans Thenans:=C[i]; -  ifAns<maxlongint Thenwriteln (ANS) -   ElseWriteln (-1); - End.

"cf707b" Bakery (idea title)