苍蝇 2009-07-04 05:46:00
点我顶贴
收藏
删除
var
a:array[1..100]of integer;
i,j,n,x,l:integer;
procedure jian(x:integer);
var i:integer;
begin
if a[x]<>0 then
begin
dec(a[x]);
for i:=x-1 downto 1 do a[i]:=9;
exit;
end;
jian(x+1);
end;
begin
readln(n);
a[1]:=1;
l:=1;
for j:=1 to n do
begin
x:=0;
for i:=1 to l do
begin
x:=x+a[i]*2;
a[i]:=x mod 10;
x:=x div 10;
end;
if x<>0 then begin l:=l+1;a[l]:=x;end;
end;
if a[1]<>0 then dec(a[1])
else jian(1);
x:=0;
for i:=1 to l do
begin
x:=x+a[i]*2;
a[i]:=x mod 10;
x:=x div 10;
end;
if x<>0 then begin inc(l); a[l]:=x; end;
for i:=l downto 1 do write(a[i]);
readln;
end.
(2^N-1)*2