SBT(pet)

原题：HNOI2004 宠物收养所

方法：SBT 维护

program size_balanced_tree;{$inline on}const    maxn=80000;type    point=^longint;var    s,l,r,w:array[0..maxn] of longint; a,b:point;    ans,m,t,k,now,root,sto:longint;procedure left(var i:longint);inline;var j:longint;begin    j:=r[i];r[i]:=l[j];l[j]:=i;    s[j]:=s[i];s[i]:=s[l[i]]+s[r[i]]+1;i:=j;end;procedure right(var i:longint);inline;var j:longint;begin    j:=l[i];l[i]:=r[j];r[j]:=i;    s[j]:=s[i];s[i]:=s[l[i]]+s[r[i]]+1;i:=j;end;procedure maintain(var t:longint; flag:boolean);inline;begin    if not flag then beginif s[l[l[t]]]>s[r[t]] then right(t) elseif s[r[l[t]]]>s[r[t]] then begin left(l[t]); right(t);end else exit;    end else beginif s[r[r[t]]]>s[l[t]] then left(t) elseif s[l[r[t]]]>s[l[t]] then begin right(r[t]); left(t);end else exit;    end;    maintain(l[t],false);    maintain(r[t],true);    maintain(t,false);    maintain(t,true);end;procedure insert(var x:longint; const k:longint);begin    if x=0 then begin inc(sto); x:=sto; w[x]:=k; s[x]:=1; exit; end;    inc(s[x]); if k<w[x] then insert(l[x],k) else insert(r[x],k);    maintain(x,k>=w[x]);end;procedure delete(var x:longint);begin    if (l[x]=0)or(r[x]=0) then begin x:=l[x]+r[x]; exit; end;    left(x);right(l[x]);delete(r[l[x]]);end;function pred(var x:longint; const k:longint):point;begin    if (x=0)or(k=w[x]) then exit(@x);    if k<w[x] then pred:=pred(l[x],k)    else beginpred:=pred(r[x],k);if pred^=0 then exit(@x);    end;end;function succ(var x:longint; const k:longint):point;begin    if (x=0)or(k=w[x]) then exit(@x);    if k>w[x] then succ:=succ(r[x],k)    else beginsucc:=succ(l[x],k);if succ^=0 then exit(@x);    end;end;function getch:char; var k:byte;begin    for k:=1 to 5 do read(getch);end;procedure readspace; var ch:char;begin repeat read(ch); until ch=' '; end;begin    assign(input,'input.txt'); reset(input);     assign(output,'output.txt'); rewrite(output);    readln(m);for m:=1 to m do beginreadln(t,k);if root=0 then now:=t;if t=now then begin insert(root,k); continue; end;a:=pred(root,k);b:=succ(root,k);if a^=0 then begin add(ans,w[b^]-k); delete(b^); end elseif b^=0 then begin add(ans,k-w[a^]); delete(a^); end elseif k-w[a^]<=w[b^]-k then    begin add(ans,k-w[a^]); delete(a^); end else    begin add(ans,w[b^]-k); delete(b^); end;     end;    writeln(ans);    close(input); close(output);end.