poj1466

求二分图的最大独立集 ＝ x + y - maxmatch;

View Code

   
     

    
      #include 
    
      <
    
      iostream
    
      >
    
      
#include 
    
      <
    
      cstdio
    
      >
    
      
#include 
    
      <
    
      cstdlib
    
      >
    
      
#include 
    
      <
    
      cstring
    
      >
    
      

    
      using
    
       
    
      namespace
    
       std;


    
      #define
    
       maxn 505
    
      


    
      int
    
       uN, vN;

    
      bool
    
       g[maxn][maxn];

    
      int
    
       xM[maxn], yM[maxn];

    
      bool
    
       chk[maxn];

    
      int
    
       n;


    
      void
    
       input()
{
 
    
      int
    
       a, m;
 memset(g, 
    
      0
    
      , 
    
      sizeof
    
      (g));
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 {
 scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      a);
 scanf(
    
      "
    
      : (%d)
    
      "
    
      , 
    
      &
    
      m);
 
    
      for
    
       (
    
      int
    
       j 
    
      =
    
       
    
      0
    
      ; j 
    
      <
    
       m; j
    
      ++
    
      )
 {
 scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      a);
 g[i][a] 
    
      =
    
       
    
      true
    
      ;
 }
 }
}


    
      bool
    
       SearchPath(
    
      int
    
       u)
{
 
    
      int
    
       v;
 
    
      for
    
       (v 
    
      =
    
       
    
      0
    
      ; v 
    
      <
    
       vN; v
    
      ++
    
      )
 
    
      if
    
       (g[u][v] 
    
      &&
    
       
    
      !
    
      chk[v])
 {
 chk[v] 
    
      =
    
       
    
      true
    
      ;
 
    
      if
    
       (yM[v] 
    
      ==
    
       
    
      -
    
      1
    
       
    
      ||
    
       SearchPath(yM[v]))
 {
 yM[v] 
    
      =
    
       u;
 xM[u] 
    
      =
    
       v;
 
    
      return
    
       
    
      true
    
      ;
 }
 }
 
    
      return
    
       
    
      false
    
      ;
}


    
      int
    
       MaxMatch()
{
 
    
      int
    
       u, ret 
    
      =
    
       
    
      0
    
      ;
 memset(xM, 
    
      -
    
      1
    
      , 
    
      sizeof
    
      (xM));
 memset(yM, 
    
      -
    
      1
    
      , 
    
      sizeof
    
      (yM));
 
    
      for
    
       (u 
    
      =
    
       
    
      0
    
      ; u 
    
      <
    
       uN; u
    
      ++
    
      )
 
    
      if
    
       (xM[u] 
    
      ==
    
       
    
      -
    
      1
    
      )
 {
 memset(chk, 
    
      false
    
      , 
    
      sizeof
    
      (chk));
 
    
      if
    
       (SearchPath(u))
 ret
    
      ++
    
      ;
 }
 
    
      return
    
       ret;
}


    
      int
    
       main()
{
 
    
      //
    
      freopen("t.txt", "r", stdin);
    
      

    
       
    
      while
    
       (scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      n) 
    
      !=
    
       EOF)
 {
 input();
 uN 
    
      =
    
       n;
 vN 
    
      =
    
       n;
 printf(
    
      "
    
      %d\n
    
      "
    
      , n 
    
      -
    
       MaxMatch() 
    
      /
    
       
    
      2
    
      );
 }
 
    
      return
    
       
    
      0
    
      ;
}