Question

PASCAL 2的幂次方 递归算法

Answer 1

不要求高精的话2的幂用shl（左移）运算最快

你是不是想要用快速幂
function f(x:longint):qword;
var
a:qword;
begin
if x=1 then f:=2 else
begin
a:=f(x div 2);
f:=a*a*(x mod 2+1)
end;
end;

Answer 2

var n:int64;
procedure work(x:int64);
var t,k:int64;
begin
if x=1 then
begin
write('2(0)');
exit;
end;
if x=2 then
begin
write('2');
exit;
end;
if x=3 then
begin
write('2+2(0)');
exit;
end;
t:=2;
k:=0;
while t<=x do
begin
t:=t*2;
k:=k+1;
end;
write('2(');
work(k);
write(')');
if (x-t div 2<>0) then
begin
write('+');
work(x-t div 2);
end;
end;
begin
readln(n);
work(n);
end.

Answer 3

readln(n);
writeln(1 shl n);
最好不要用递归

Answer 4

题解么？

Answer 5

题解？