组合问题 ZOJ 1089 Lotto

组合问题

Lotto

   
     

    
      
    
       1 
    
      #include
    
      <
    
      iostream
    
      >
    
      

    
       2 
    
       
    
      using
    
       
    
      namespace
    
       std;

    
       3 
    
       
    
      int
    
       m;

    
       4 
    
       
    
      int
    
       n 
    
      =
    
       
    
      6
    
      ;

    
       5 
    
      
    
      int
    
       b[
    
      13
    
      ];

    
       6 
    
      
    
      int
    
       c[
    
      13
    
      ];

    
       7 
    
      
    
      void
    
       combination(
    
      int
    
      , 
    
      int
    
      );

    
       8 
    
      

    
       9 
    
      
    
      int
    
       main()

    
      10 
    
      {

    
      11 
    
       
    
      int
    
       num;

    
      12 
    
       
    
      //
    
      freopen("test.txt","r", stdin);
    
      

    
      13 
    
      
    
       cin 
    
      >>
    
       num;

    
      14 
    
       
    
      while
    
       (num)

    
      15 
    
       {

    
      16 
    
       
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       num; i
    
      ++
    
      )

    
      17 
    
       {

    
      18 
    
       cin 
    
      >>
    
       c[i];

    
      19 
    
       }

    
      20 
    
       m 
    
      =
    
       num;

    
      21 
    
       combination(
    
      0
    
      ,
    
      0
    
      );

    
      22 
    
       cin 
    
      >>
    
       num;

    
      23 
    
       
    
      if
    
       (num)

    
      24 
    
       cout 
    
      <<
    
       endl;

    
      25 
    
       }

    
      26 
    
       

    
      27 
    
       
    
      return
    
       
    
      0
    
      ;

    
      28 
    
      }

    
      29 
    
      

    
      30 
    
      
    
      //
    
      计算组合数

    
      31 
    
      
    
      //
    
      m个里面取6个出来
    
      

    
      32 
    
      
    
      void
    
       combination(
    
      int
    
       i, 
    
      int
    
       current)

    
      33 
    
      {

    
      34 
    
       
    
      if
    
       (i 
    
      >=
    
       n)

    
      35 
    
       {

    
      36 
    
       
    
      for
    
       ( 
    
      int
    
       j 
    
      =
    
       
    
      0
    
      ; j 
    
      <
    
       n; j
    
      ++
    
      )

    
      37 
    
       {

    
      38 
    
       
    
      if
    
       (j 
    
      ==
    
       n
    
      -
    
      1
    
      ) 

    
      39 
    
       cout 
    
      <<
    
       b[j]; 

    
      40 
    
       
    
      else
    
      

    
      41 
    
       cout 
    
      <<
    
       b[j] 
    
      <<
    
       
    
      "
    
       
    
      "
    
      ; 

    
      42 
    
       }

    
      43 
    
       cout 
    
      <<
    
       endl;

    
      44 
    
       }

    
      45 
    
       
    
      else
    
      

    
      46 
    
       {

    
      47 
    
       
    
      for
    
       (
    
      int
    
       j 
    
      =
    
       current; j 
    
      <
    
       m
    
      -
    
      n
    
      +
    
      i
    
      +
    
      1
    
      ; j
    
      ++
    
      )
    
      //
    
      这里j的上限做了优化，减小不必要的分枝
    
      

    
      48 
    
      
    
       {

    
      49 
    
       b[i] 
    
      =
    
       c[j];

    
      50 
    
       combination(i
    
      +
    
      1
    
      , j
    
      +
    
      1
    
      );

    
      51 
    
       }

    
      52 
    
       }

    
      53 
    
      }