Hoj 2472 IR-Lab

/*

Question:

 

On-duty questions: give everyone their spare time and ask if they can schedule a person on duty at every time.

 

Analysis:

The problem of binary matching is illustrated by the link between a person and his spare time. Then the hungry algorithm is simple.

*/

 

# Include
<Iostream>

 

# Include
<Cstring>

 

# Include
<Cstdio>

 

Using namespace
Std;

 

# Define X 22

 

Bool
G [X] [X], use [X];

 

Int
Xm [X], ym [X], k, p;

 

Bool dfs (int u)

 

{

 

For (int v = 0; v <k; v ++)

 

If (g [u] [v] &! Use [v])

 

{

 

Use [v] = true;

 

If (ym [v] =-1 | dfs (ym [v])

 

{

 

Xm [u] = v;

 

Ym [v] = u;

 

Return true;

 

}

 

}

 

Return false;

 

}

 

Int hungry ()

 

{

 

Int ret = 0;

 

Memset (xm,-1, sizeof (xm ));

 

Memset (ym,-1, sizeof (ym ));

 

For (int u = 0; u <p; u ++)

 

If (xm [u] =-1)

 

{

 

Memset (use, false, sizeof (use ));

 

If (dfs (u ))

 

Ret ++;

 

}

 

Return ret;

 

}

 

Int main ()

 

{

 

Freopen ("sum. in", "r", stdin );

 

Freopen ("sum. out", "w", stdout );

 

While (cin> k> p, k | p)

 

{

 

Int t, x;

 

Memset (g, false, sizeof (g ));

 

For (int I = 0; I <p; I ++)

 

{

 

Scanf ("% d", & t );

 

While (t --)

 

{

 

Scanf ("% d", & x );

 

G [I] [x] = true; // This person is connected to his/her spare time.

 

}

 

}

 

If (hungry () = k) // if yes

 

Printf ("yes \ n ");

 

Else

 

Printf ("no \ n ");

 

// Printf ("% d \ n", hungry ());

 

}

 

Return 0;

 

}