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Discussion of Problem 1114. Boxes

I go WA!!! Help me plese give some tests!
Posted by Algorithmus_UA(algorithmus@univ.kiev.ua) 31 Oct 2002 02:56
type
 long = record
              a:array[1..250]of byte;
              l:byte;
        end;
procedure add(var a,b:long);
var l,c,k,i:byte;
begin
  k:=0;
  if a.l>b.l then l:=a.l else l:=b.l;
  i:=1;
  for i:=1 to l do
  begin
    c:=a.a[i];
    a.a[i]:=(c+b.a[i]+k)mod 10;
    k:=(c+b.a[i]+k)div 10;
  end;
  a.l:=i;
  if k<>0 then
  begin
    inc(a.l);
    a.a[a.l]:=K;
  end;
end;

procedure mul_i(var a:long;b:longint);
var k:longint;c,i:byte;
begin
  k:=0;
  i:=1;
  for i:=1 to a.l do
  begin
    c:=a.a[i];
    a.a[i]:=(c*b+k)mod 10;
    k:=(c*b+k)div 10;
  end;
  a.l:=i;
  while k<>0 do
  begin
    inc(a.l);
    a.a[a.l]:=K mod 10;
    k:=k div 10;
  end;
end;

procedure mul(var a,b:long);
var tmp,_a:long;
    i,j:byte;
begin
  fillchar(tmp,sizeof(tmp),0);
  for i:=1 to b.l do
  begin
    _a:=a;
    mul_i(_a,b.a[i]);
    for j:=_a.l downto 1 do _a.a[j+i-1]:=_a.a[j];
    for j:=1 to i-1 do _a.a[j]:=0;
    _a.l:=_a.l+i-1;
    add(tmp,_a);
  end;
{  i:=tmp.l;
  for i:=tmp.l downto 1 do if tmp.a[i]<> 0 then break;
  tmp.l:=i;}
  a:=tmp;
end;

var c:array[0..15]of extended;
    N,A,B,MMM:longint;
    i,j:integer;
    tmp:extended;
function cnk(N,K:integer):longint;
var s:longint;
    i:integer;
begin
  s:=1;
  for i:=K+1 to N do
  s:=s*i div (i-K);
  cnk:=s;
end;

var _a,_b:long;
begin
{  cnk(20,10);}
{  assign(input,'1114.dat');reset(input);}
  readln(N,A,B);
  if A>B then mmm:=A else mmm:=B;
  c[0]:=1;
  for i:=1 to mmm do
  begin
    {for j:=i-1 downto 0 do} c[i]:=c[i]+c[i-1];
    for j:=1 to i do
    begin
      c[i]:=c[i]+cnk(N,j)*cnk(i-1,j-1);
    end;
  end;
  tmp:=c[a];
  for i:=1 to 25 do
  begin
    _a.a[i]:=trunc(tmp-int(tmp/10)*10);
    tmp:=int(tmp/10);
  end;
  i:=25;
  for i:=25 downto 1 do if _a.a[i]<>0 then break;
  _a.l:=i;
  tmp:=c[b];
  for i:=1 to 25 do begin _b.a[i]:=trunc(tmp-int(tmp/10)*10);tmp:=int
(tmp/10);end;
  i:=25;
  for i:=25 downto 1 do if _b.a[i]<>0 then break;
  _b.l:=i;
  mul(_a,_b);
  for i:=_a.l downto 1 do write(_a.a[i]);
  writeln;
{  writeln(c[A]*c[B]:0:0);}
end.