Acm hdu 2444 the accomodation of students (determine whether it is a two-part graph, and then find the maximum matching)

Question link: http://acm.hdu.edu.cn/showproblem.php? PID = 1, 2444

Question:

Yes N Students, including M People know each other. Each person can be assigned a room and asked if they can N The students are divided into two parts. The students in each part do not know each other, but the students in the two parts do not know each other. If it can be divided into two parts, the maximum number of rooms is calculated; otherwise, the output is No .

Analysis:

First, determine whether it is a two-part graph, and then find the maximum matching.

 

HereProgramHungary ()UseVectorImplementation

 /*  
HDU 2444 the accomodation of Students

  */  
# Include <  Iostream  >  
# Include  <  String  . H  >  
# Include  <  Vector  >  
  Using     Namespace  STD;
 # Define  Maxn 202  
Vector  <  Int  >  Ev [maxn];
  Int  Linker [maxn];
  Bool  Used [maxn];
  Int  UN;
  Int  Matchs [maxn], CNT [maxn];
  Bool DFS (  Int  U)
{
  Int  I;
  For  (I  =  0  ; I  <  Ev [u]. Size (); I  ++  )
{
  Int  V  = Ev [u] [I];
  If  (  !  Used [v])
{
Used [v]  =  True  ;
  If  (Linker [v]  =-  1  |  DFS (linker [v])
{
Linker [v]  =  U;
 Return     True  ;
}
}
}
  Return     False  ;
}
  Int  Hungary ()
{
  Int  Res  =  0  ;
  Int U;
Memset (linker,  -  1  ,  Sizeof  (Linker ));
  For  (U  =  1  ; U  <=  UN; u  ++  )
{
Memset (used,  False  , Sizeof  (Used ));
  If  (DFS (u) res  ++  ;
}
  Return  Res;
}
  Bool  Judge (  Int  X,  Int  Y)
{
  Int  I;
  For (I  =  0  ; I  <  Ev [X]. Size (); I  ++  )
{
  If  (CNT [EV [x] [I]  =  0  )
{
CNT [EV [x] [I]  =-  1  * Y;
Matchs [EV [x] [I]  =  True  ;
  If  (  !  Judge (EV [x] [I],  -  1  *  Y ))  Return     False  ;
}
  Else    If  (CNT [EV [x] [I]  =  Y)  Return     False  ;
}
  Return     True  ;
}
  Bool  Matched ()
{
  Int  I;
Memset (matchs, False  ,  Sizeof  (Matchs ));
  For  (I  =  1  ; I  <=  UN; I  ++  )
{
  If  (EV [I]. Size ()  &&! Matchs [I])
{
Memset (CNT,  0  ,  Sizeof  (CNT ));
CNT [I]  =-  1  ;
Matchs [I]  =  True  ;
  If  (  !  Judge (I,  - 1  ))  Return     False  ;
}
}
  Return     True  ;
}
  Int  Main ()
{
  Int  M;
  Int  I;
  Int U, V;
  While  (Scanf (  "  % D  "  ,  &  UN,  &  M)  ! =  EOF)
{
  For  (I  =  1  ; I <=  UN; I  ++  )
  If  (EV [I]. Size () eV [I]. Clear ();
  While  (M  --  )
{
Scanf (  "  % D  "  ,  &  U,  & V );
Ev [u]. push_back (v );
Ev [v]. push_back (U );
}

  If  (Matched ())
Printf (  "  % D \ n  "  , Hungary ()  /  2  );
  Else  Printf (  "  No \ n  " );
}
  Return     0  ;
}