(a+b+c)3=((a+b)+c)3=(a+b)3+c3+3(a+b)c(a+b+c)(a+b+c)3=((a+b)+c)3=(a+b)3+c3+3(a+b)c(a+b+c)
=a3+b3+3ab(a+b)+c3+3(a+b)c(a+b+c)=a3+b3+3ab(a+b)+c3+3(a+b)c(a+b+c)
=a3+b3+c3+3(a+b)(ab+c(a+b+c))=a3+b3+c3+3(a+b)(ab+c(a+b+c))
=a3+b3+c3+3(a+b)(ab+ac+bc+c2)=a3+b3+c3+3(a+b)(ab+ac+bc+c2)
=a3+b3+c3+3(a+b)(a+c)(b+c)=a3+b3+c3+3(a+b)(a+c)(b+c)

~~

ĐÁP ÁN VÒNG 2 CUỘC THI TIN HỌC:

* ĐỀ 1:

Câu 1:

CÂU 1:
const fi='uc.inp';
fo='uc.out';
var f: text;
a,b,c : integer;
function uc(x,y): integer;
var z: integer;
begin
while y<>0 do
begin
z:=x mod y;
x:=y;
y:=z;
end;
uc:=x;
end;
procedure ip;
begin
assign(f,fi);
reset(f);
read(f,a,b,c);
close(f);
end;
procedure out;
begin
assign(f,fo);
rewrite(f);
write(f,uc(uc(a,b),c);
close(f);
end;
begin
ip;
out;
end.

Câu 2:

const fi='SN.inp';
fo='SN.out';
var
f:text;
i,n:integer;
s:real;
procedure ip;
begin
assign(f,fi);
reset(f);
read(f,n);
close(f);
end;
procedure out;
begin
assign(f,fo);
rewrite(f);
s:=0;
for i:= 1 to n do
begin
if i mod 2 <> 0 then
s:=s+(i/(i+1));
if i mod 2 = 0 then
s:=s-(i/(i+1));
end;
write(f,s:0:2);
close(f);
end;
BEGIN
ip;
out;
END.

Câu 3:

const fi='SSNT.inp';
fo='SSNT.out';
var
f:text;
n,i,max,j:integer;
s:string;
a:array[1..32000] of integer;
function nt(x:integer):boolean;
var
i:integer;
begin
nt:=false;
if x < 2 then exit;
for i:= 2 to trunc(sqrt(x)) do
if x mod i = 0 then exit;
nt:=true;
end;
function snt(x:integer):boolean;
begin
snt:=false;
if x= 0 then exit;
while nt(x) = true do
x := x div 10;
if x = 0 then snt:=true;
end;
procedure ip;
begin
assign(f,fi);
reset(f);
max:=a[1];
readln(f,n);
for i:= 1 to n do
begin
read(f,a[i]);
if( a[i] < max ) and (nt(a[i]) = true) then
max:=a[i];
end;
close(f);
end;
procedure out;
begin
assign(f,fo);
rewrite(f);
writeln(f,max);
max:=0;
for i:= 1 to n do
begin
if snt(a[i]) = true then
begin
str(a[i],s);
if length(s) = 2 then
max:=max+a[i];
s:='';
end
else
a[i]:=-32000;
end;
writeln(f,max);
for i:= 1 to n-1 do
for j :=i+1 to n do
if a[i] > a[j] then
begin
max:=a[i];
a[i]:=a[j];
a[j]:=max;
end;
for i:= 1 to n do
if (a[i] > 0) and (a[i] <> a[i-1]) then write(f,a[i],' ');
close(f);
end;
BEGIN
ip;
out;
END.

CÂU 4:

const fi='TUOI.INP';
fo='TUOI.OUT';
var f: text;
a,b: byte;
procedure ip;
begin
assign(f,fi);
reset(f);
read(f,a,b);
close(f);
end;
procedure out;
begin
assign(f,fo);
rewrite(f);
if (x=y*2) and (x>18) and (x-y>=18) then write(f,'CO') else write(f,x-y*2);
close(f);
end;
begin
ip;
out;
end.

const fi='CM.INP';

fo='CM.OUT';

var f: text;

a,n,b,k: integer;

a1: array[1..32000] of integer;

function nt(x: integer): boolean;

var i: integer;

begin

nt:=false;

if x<2 then exit;

for i:=2 to trunc(sqrt(x)) do if x mod i=0 then exit;

nt:=true;

end;

procedure ip;

begin

assign(f,fi);

reset(f);

read(f,n);

close(f);

end;

procedure out;

begin

assign(f,fo);

rewrite(f);

d:=0;

for a:=1 to k do

if nt(a) then

begin

inc(d);

a1[d]:=a;

end;

for a:=1 to d do

for b:=x to d do

if a1[a]+a1[b]=k then writeln(f,a1[a],'+',a1[b]);

end;

close(f);

end;

begin

ip;

out;

end.

*ĐỀ 2 :

BÀI LÀM CỦA BẠN LÊ HOÀNG THẮNG:

//----------------------------CAU 1--------------------------------

var s,d,n,i,u:longint;
a:array[0..32001] of longint;
f:text;
function ucln(x,y:longint):longint;
begin
if y=0 then exit(x) else exit(ucln(y,x mod y));
end;
begin
assign(f,'ucln.inp');reset(f);
readln(f,n);
for i:=1 to n do read(f,a[i]); close(f);
u:=a[1];
for i:=2 to n do u:=ucln(u,a[i]);
assign(f,'ucln.out');rewrite(f);
write(f,'UCLN: ',u,'; UC: ');
for i:=1 to u do if u mod i=0 then
begin
if i<>u then write(f,i,',') else write(f,i);
if i<10 then inc(d) else inc(s,i);
end;
writeln(f);
writeln(f,d); write(f,s);
close(f);
end.

//----------------------------CAU 2--------------------------------

var n,i:longint;
s:real;
f:text;
begin
assign(f,'sn.inp');reset(f);
readln(f,n); close(f);
for i:=1 to n do if odd(i) then s:=s-i/(i+1) else s:=s+i/(i+1);
assign(f,'sn.out');rewrite(f);
write(f,s:0:2);
close(f);
end.

//----------------------------CAU 3--------------------------------

var a:array[0..1000000] of boolean;
b:array[0..1000000] of longint;
i,j,k,n,d:longint;
f:text;
procedure taosang(n:longint);
var i,j:longint;
begin
for i:=2 to trunc(sqrt(n)) do if not(a[i]) then
begin
j:=i*i;
while j<=n do begin a[j]:=true; inc(j,i); end;
end;
end;
begin
assign(f,'boso.inp');reset(f);
readln(f,n); taosang(n); close(f);
assign(f,'boso.out');rewrite(f);
for i:=2 to n do if not(a[i]) then
begin
inc(d);
b[d]:=i;
end;
for i:=1 to d do
for j:=i to d do
if (n-b[i]-b[j]>=b[j]) and not(a[n-b[i]-b[j]]) then
writeln(f,b[i],' ',b[j],' ',n-b[i]-b[j]);
close(f);
end.

//----------------------------CAU 4--------------------------------

THAM KHẢO ĐỀ 1.

//----------------------------CAU 5--------------------------------

var n,i,s,t:longint;
f:text;
begin
assign(f,'u.inp');reset(f);
readln(f,n); t:=n; close(f);
assign(f,'u.out');rewrite(f);
for i:=2 to trunc(sqrt(n)) do
begin
if n mod i=0 then
begin
write(f,i,' ');
repeat n:=n div i until n mod i>0;
end;
if t mod (i*i)=0 then inc(s,i*i);
end;
writeln(f);
write(f,s+1);
close(f);
end.

*ĐỀ CHUNG:

BÀI LÀM CỦA BẠN ĐÀO XUÂN SƠN :

Câu 1:

const fi='TCS.inp';
fo='TCS.out';
var
f:text;
x:char;
tg:byte;
s:integer;
CODE:integer;
procedure ip;
begin
assign(f,fi);
reset(f);
s:=0;
while not(eof(f)) do
begin
read(f,x);
if x in ['0'..'9'] then
begin
val(x,tg,CODE);
s:=s+tg;
end;
end;
close(f);
end;
procedure out;
begin
assign(f,fo);
rewrite(f);
write(f,s);
close(f);
end;
BEGIN
ip;
out;
END.

Câu 2:

const fi='t.inp';
fo='t.out';
var
f:text;
s:string;
i:byte;
procedure ip;
begin
assign(f,fi);
reset(f);
read(f,s);
close(f);
end;
procedure out;
begin
assign(f,fo);
rewrite(f);
s[1]:=upcase(s[1]);
for i:= 2 to length(s) do
if s[i-1] <> #32 then
s[i]:=lowercase(s[i]) else
s[i]:=upcase(s[i]);
write(f,s);
close(f);
end;
BEGIN
ip;
out;
END.

Cách sử dụng file cho các bạn chưa hiểu biết :

const fi='<ten>.inp';

fo='<ten>.out';

var <các biến cần thiết cho bài toán> : <kiểu dữ liệu phù hợp với biến>;

f : text ;

producere ip;

begin

{Dữ liệu vào};

assign(f,fi);

reset(f);

{Nhập theo yêu cầu của bài toán}; {VD nhập vào số nguyên n :} read(f,n);

close(f);

end;

{dữ liệu ra};

procedure out;

begin

assign(f,fo);

rewrite(f);

{Khai triển thuật toán}; {VD tính tổng 2 số a và b };

T:=a;

T:=T+b;

write(f,T);

close(f);

end;

BEGIN

ip;

out;

END.

Chú ý : Những phần in đậm cần thiết trong tệp .

cạnh bc là :  30 m