DTTUI1 - Cái túi 1
Tác giả: flashmt
Ngôn ngữ: Pascal
const fi='';
fo='';
maxn=40;
maxc=1048575;
var n,re,m,mid,max,num:longint;
v,w:array[1..40] of longint;
f,g:array[0..maxc] of longint;
procedure rf;
var i:longint;
begin
read(n,m);
for i:=1 to n do read(w[i],v[i]);
end;
procedure calc;
var i,j:longint;
begin
max:=1 shl mid-1;
for i:=1 to max do
for j:=0 to mid-1 do
if (i shr j) and 1=1 then
begin
f[i]:=f[i]+w[j+1];
g[i]:=g[i]+v[j+1];
end;
end;
procedure sort(l,r:longint);
var i,j,x,y,t:longint;
begin
i:=l; j:=r; x:=f[(i+j) shr 1]; y:=g[(i+j) shr 1];
repeat
while (f[i]<x) or ((f[i]=x) and (g[i]>y)) do i:=i+1;
while (f[j]>x) or ((f[j]=x) and (g[j]<y)) do j:=j-1;
if i<=j then
begin
t:=f[i]; f[i]:=f[j]; f[j]:=t;
t:=g[i]; g[i]:=g[j]; g[j]:=t;
i:=i+1; j:=j-1;
end;
until i>j;
if i<r then sort(i,r);
if l<j then sort(l,j);
end;
procedure edit;
var i:longint;
begin
num:=0;
for i:=1 to max do
if g[i]>g[num] then
begin
num:=num+1;
f[num]:=f[i];
g[num]:=g[i];
end;
end;
function bs(t:longint):longint;
var l,r,md,i:longint;
begin
l:=0; r:=num;
while l<=r do
begin
md:=(l+r) shr 1;
if f[md]=t then break;
if f[md]<t then l:=md+1
else r:=md-1;
end;
if f[md]=t then bs:=md
else
begin
for i:=md+1 downto md-1 do
if (i>=0) and (i<=num) and (f[i]<=t) then
begin
bs:=i; exit;
end;
end;
end;
procedure pr;
var i,l,ww,vv,j,x:longint;
begin
mid:=(n+1) shr 1;
calc;
sort(1,max);
edit;
l:=mid+1; mid:=n-mid;
max:=1 shl mid-1;
re:=0;
for i:=0 to max do
begin
ww:=0; vv:=0;
for j:=0 to mid-1 do
if (i shr j) and 1=1 then
begin
ww:=ww+w[l+j];
vv:=vv+v[l+j];
end;
if ww<=m then
begin
x:=bs(m-ww);
if vv+g[x]>re then re:=vv+g[x];
end;
end;
end;
procedure wf;
begin
writeln(re);
end;
begin
assign(input,fi); reset(input);
assign(output,fo); rewrite(output);
rf;
pr;
wf;
close(input); close(output);
end.