NOIXICH - Nối Xích

Tác giả: flashmt

Ngôn ngữ: Pascal

var a:array[1..20000] of integer;
    n,re:integer;
procedure rf;
var i:integer;
begin
     readln(n);
     for i:=1 to n do
     begin
          while eoln do readln;
          read(a[i]);
     end;
end;

procedure sort(l,r:integer);
var i,j,x,y:integer;
begin
     i:=l; j:=r; x:=a[(i+j) div 2];
     repeat
           while a[i]<x do inc(i);
           while a[j]>x do dec(j);
           if i<=j then
           begin
                y:=a[i]; a[i]:=a[j]; a[j]:=y;
                inc(i); dec(j);
           end;
     until i>j;
     if i<r then sort(i,r);
     if l<j then sort(l,j);
end;

procedure pr;
var i,t:integer;
begin
     sort(1,n);
     re:=0; t:=n-1;
     for i:=1 to n do
     begin
          if a[i]>=t-1 then
          begin
               re:=re+t-1;
               if a[i]>t-1 then inc(re);
               break;
          end
          else
          begin
               re:=re+a[i];
               t:=t-a[i]-1;
          end;
     end;
end;

procedure wf;
begin
     write(re);
end;

begin
     rf;
     pr;
     wf;
end.

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