bzoj3632

裸的最大团，随机化大法好

多次随机出一个选择顺序然后贪心即可

var b:array[0..51,0..51] of boolean;
    a:array[0..51] of longint;
    v:array[0..51] of boolean;
    n,m,i,j,x,y,ans:longint;

procedure swap(var a,b:longint);
  var c:longint;
  begin  
    c:=a;
    a:=b;
    b:=c;
  end;
  
procedure work;
  var i,j,s:longint;
  begin
    s:=0;
    fillchar(v,sizeof(v),false);
    for i:=1 to n do
      if not v[a[i]] then
      begin
        v[a[i]]:=true;
        for j:=i+1 to n do
          if not b[a[i],a[j]] then v[a[j]]:=true;
        inc(s);
      end;
    if ans<s then ans:=s;
  end;

begin
  readln(n);
  while not eof do 
  begin
    readln(x,y);
    b[x,y]:=true;
    b[y,x]:=true;
  end;
  for i:=1 to n do
    a[i]:=i;
  work;
  for i:=1 to 15000 do
  begin
    for j:=2 to n do
      swap(a[j],a[trunc(random*j)+1]);
    work;
  end;
  writeln(ans);
end.