和平委员会 2-sat

按照2-sat的套路直接写就好了...由于要求输出字典序最小的方案数，所以在新图上处理的时候按字典序最小的拓扑序进行染色（不用dfs进行传递）

uses math;
var
n,m,l,x,y,tt :longint;
time,top,size :longint;
i :longint;
vis :array[0..160010] of boolean;
last,la,z :array[0..160010] of longint;
pre,other,pr,ot :array[0..40010] of longint;
belong,dfn,low :array[0..160010] of longint;
anti,color,indu :array[0..160010] of longint;
work,heap :array[0..160010] of longint;

procedure swap(var a,b:longint);
var
c:longint;
begin
c:=a; a:=b; b:=c;
end;

procedure connect(x,y:longint);
begin
inc(l);
pre[l]:=last[x];
last[x]:=l;
other[l]:=y;
end;

procedure connect2(x,y:longint);
begin
inc(l);
pr[l]:=la[x];
la[x]:=l;
ot[l]:=y;
end;

procedure dfs(x:longint);
var
p,q,cur:longint;
begin
inc(time);
low[x]:=time;
dfn[x]:=time;
inc(top);
z[top]:=x;
vis[x]:=true;
//
q:=last[x];
while q<>0 do
begin
p:=other[q];
if (dfn[p]=0) then
begin
dfs(p);
low[x]:=min(low[x],low[p]);
end else
if vis[p] then low[x]:=min(low[x],dfn[p]);
q:=pre[q];
end;
//
if low[x]=dfn[x] then
begin
cur:=-1; inc(tt);
while cur<>x do
begin
cur:=z[top];
dec(top);
vis[cur]:=false;
belong[cur]:=tt;
end;
end;
end;

procedure rebuild;
var
i,p,q:longint;
begin
l:=0;
for i:=1 to n<<1 do
begin
q:=last[i];
while q<>0 do
begin
p:=other[q];
if belong[i]<>belong[p] then
begin
connect2(belong[p],belong[i]);
inc(indu[belong[i]]);
end;
q:=pre[q];
end;
end;
end;

procedure heap_down(i:longint);
var
t:longint;
begin
while (i<<1)<=size do
begin
if heap[i]<heap[i<<1] then t:=i else t:=i<<1;
if (i<<1)+1<=size then
if heap[t]>heap[(i<<1)+1] then t:=(i<<1)+1;
if i<>t then
begin
swap(heap[i],heap[t]);
i:=t;
end else exit;
end;
end;

procedure heap_up(i:longint);
begin
if i=1 then exit;
while i>1 do
4000
begin
if heap[i]<heap[i>>1] then
begin
swap(heap[i],heap[i>>1]);
i:=i>>1;
end else exit;
end;
end;

procedure insert(x:longint);
begin
inc(size);
heap[size]:=x;
heap_up(size);
end;

procedure topsort_col;
var
p,q:longint;
begin
while size<>0 do
begin
x:=heap[1];
heap[1]:=heap[size]; dec(size); heap_down(1);
if color[x]=0 then
begin
color[x]:=1;
color[anti[x]]:=2;
end;
q:=la[x];
while q<>0 do
begin
p:=ot[q];
dec(indu[p]);
if indu[p]=0 then insert(p);
q:=pr[q];
end;
end;
end;

begin
assign(input,'spo.in');reset(input);
assign(output,'spo.out');rewrite(output);
read(n,m);
for i:=1 to m do
begin
read(x,y);
if (y and 1=1) then connect(x,y+1) else connect(x,y-1);
if (x and 1=1) then connect(y,x+1) else connect(y,x-1);
end;
for i:=1 to n<<1 do if dfn[i]=0 then dfs(i);
for i:=1 to n do
if (belong[i<<1]=belong[(i<<1)-1]) then
begin
writeln('NIE'); close(input); close(output); exit;
end;
rebuild;
for i:=1 to n do
begin
anti[belong[i<<1]]:=belong[(i<<1)-1];
anti[belong[(i<<1)-1]]:=belong[i<<1];
end;
for i:=1 to tt do if indu[i]=0 then insert(i);
topsort_col;
//
for i:=1 to n<<1 do
if color[belong[i]]=1 then writeln(i);
close(input); close(output);
end.
——by Eirlys