练习

/*
将标号为1.2.3.4.5.6的6张卡片放入3个不同的信封，
若每个信封放2张，有多少种放法
*/
#define NUM_OF_ENVELOPE ( 3 )
#define MAX_NUM_IN_ENVELOPE ( 2 )
#define NUM_OF_CARD ( 6 )
#define BEGIN ( 0 )
#define END ( NUM_OF_CARD + 1 )
#define RECORD ( MAX_NUM_IN_ENVELOPE - 1 + 1 )
#define NOTHING ( 0 )
#include <stdio.h>
#include <stdlib.h>
void put_card_to_envelope(void);
void out_put(int (*)[ MAX_NUM_IN_ENVELOPE + 1 ] , int , int );
int main( void )
{
  put_card_to_envelope();
  system("PAUSE");
  return 0;
}
void put_card_to_envelope(void)
{
    static int num_of_card = BEGIN ;
    static int envelope[ NUM_OF_ENVELOPE ][ MAX_NUM_IN_ENVELOPE + 1 ] = {NOTHING};
    static int kinds_of_put_method = 0 ;
    switch( num_of_card ){
         int i , j ;
         case BEGIN :
            num_of_card ++ ;
            put_card_to_envelope();
            printf( "有%d种放法\n" , kinds_of_put_method ) ;
            num_of_card = BEGIN ;
            kinds_of_put_method = 0 ;
            break;
         default :
            for( i = 0 ; i < NUM_OF_ENVELOPE ; i++ )
            {
              if( envelope[ i ][ RECORD ] < MAX_NUM_IN_ENVELOPE ){
                  envelope[ i ][ envelope[i][RECORD] ] = num_of_card ;
                  envelope[ i ][ RECORD ] ++ ;
                  num_of_card++;
                  put_card_to_envelope();
                  num_of_card--;
                  envelope[ i ][ RECORD ] -- ;
                  envelope[ i ][ envelope[ i ][ RECORD ] ] = NOTHING ;
              }
            }
            break;
         case END :
            out_put( envelope , NUM_OF_ENVELOPE , MAX_NUM_IN_ENVELOPE );
            kinds_of_put_method++;
            break;
         }
}
void out_put(int (*p_en)[ MAX_NUM_IN_ENVELOPE + 1 ] , int n_en , int max_num )
{
    int i , j ;
    for( i = 0 ; i< n_en ; i ++ ){
      for( j = 0 ; j < max_num ; j++ ){
         printf("%d " , p_en[i][j] );
       }
      putchar('|');
    }
    putchar('\n');
}