[CodeVS1036] 商务旅行

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http://codevs.cn/problem/1036/

题目大意

题解

lca裸题

const maxn=30005;var st:array[0..maxn,0..20]of longint; w:array[0..4*maxn,1..2]of longint; dep,t:array[0..maxn]of longint; i,j,k:longint; n,m,len,a,b,head,tail,tt,v,maxd,ans:longint;procedure init(a,b:longint);begin w[len,1]:=b; if w[a,2]=0 then w[a,2]:=len else w[w[a,1],2]:=len; w[a,1]:=len; inc(len);end;function lca(a,b:longint):longint;var i:longint;begin if dep[a]>dep[b] then begin i:=a; a:=b; b:=i; end; for i:=trunc(ln(maxd)/ln(2)) downto 0 do  if dep[st[b,i]]>=dep[a] then b:=st[b,i]; if a=b then exit(a); for i:=trunc(ln(maxd)/ln(2)) downto 0 do  if st[a,i]<>st[b,i]  then begin a:=st[a,i]; b:=st[b,i]; end; exit(st[a,0]);end;begin readln(n); len:=n+1; for i:=1 to n-1 do  begin readln(a,b); init(a,b); init(b,a); end; t[1]:=1; head:=1; tail:=2; dep[1]:=1; maxd:=1; while head<tail do  begin   v:=t[head]; inc(head); tt:=w[v,2];   while tt<>0 do    begin     if dep[w[tt,1]]=0 then begin      dep[w[tt,1]]:=dep[v]+1;      t[tail]:=w[tt,1]; inc(tail);      st[w[tt,1],0]:=v; if dep[v]+1>maxd then maxd:=dep[v]+1;     end;     tt:=w[tt,2];    end;  end; for j:=1 to trunc(ln(maxd)/ln(2)) do  for i:=1 to n do   st[i,j]:=st[st[i,j-1],j-1]; readln(m); v:=1; ans:=0; for i:=1 to m do  begin   readln(a);   inc(ans,dep[a]+dep[v]-2*dep[lca(v,a)]);   v:=a;  end; writeln(ans);end.

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