HNOI2002营业额统计（平衡树）

标准的平衡树。

贴个splay吧

var

 v,l,r,fa:array[0..100000] of longint;

 root,x,i,n,ans:longint;

procedure zig(x:longint);

 var y,z:longint;

 begin

 y:=fa[x];z:=fa[y];

 if root=y then root:=x;

 l[y]:=r[x];

 if r[x]<>0 then fa[r[x]]:=y;

 r[x]:=y;

 fa[y]:=x;

 fa[x]:=z;

 if z=0 then exit;

 if l[z]=y then l[z]:=x else r[z]:=x;

 end;

procedure zag(x:longint);

 var y,z:longint;

 begin

 y:=fa[x];z:=fa[y];

 if root=y then root:=x;

 r[y]:=l[x];

 if l[x]<>0 then fa[l[x]]:=y;

 l[x]:=y;

 fa[y]:=x;

 fa[x]:=z;

 if z=0 then exit;

 if l[z]=y then l[z]:=x else r[z]:=x;

 end;

procedure splay(x:longint);

 var y,z:longint;

 begin

 while x<>root do

  begin

  y:=fa[x];

  if y=root then

   begin

   if x=l[y] then zig(x) else zag(x);

   exit;

   end;

  z:=fa[y];

  if l[y]=x then

   if l[z]=y then

    begin

     zig(y);zig(x)

    end

   else

    begin

     zig(x);zag(x);

    end

  else

   if r[z]=y then

    begin

     zag(y);zag(x);

    end

   else

    begin

     zag(x);zig(x);

    end;

  end;

 end;

procedure insert(x,k:longint);

 var i,j:longint;

 begin

 if root=0 then

  begin

  root:=k;

  v[k]:=x;l[k]:=0;r[k]:=0;fa[k]:=0;

  exit;

  end;

 i:=root;

 v[k]:=x;

 while true do

  begin

  if x<=v[i] then j:=l[i] else j:=r[i];

  if j=0 then

   begin

    if x<=v[i] then l[i]:=k else r[i]:=k;

    fa[k]:=i;

    break;

   end;

  i:=j;

  end;

 splay(k);

 end;

function min(x,k:longint):longint;

 var i,j,tmp:longint;

 begin

 tmp:=maxlongint;

 i:=l[k];

 while i<>0 do

  begin

   if abs(v[i]-x)<tmp then begin tmp:=abs(v[i]-x);j:=i;end;

   i:=r[i];

  end;

 i:=r[k];

 while i<>0 do

  begin

   if abs(v[i]-x)<tmp then begin tmp:=abs(v[i]-x);j:=i;end;

   i:=l[i];

  end;

 splay(j);

 exit(tmp);

 end;

begin

 read(n);

 ans:=0;

 for i:=1 to n do

  begin

   read(x);

   insert(x,i);

   if i<>1 then ans:=ans+min(x,i) else ans:=x;

  end;

 writeln(ans);

end.                      

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