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PLSQL算24点
 
 
    很早以前就想用PLSQL写一个算24点的程序了,后来想了一下没有研究下去,最近上ITPUB的时候正好大家都在讨论,在大牛的基础上修改了一下,基本上思想和算法都是没有变的,就是学习了一下。还有两个大问题没有处理好,一是只用了枚举法,用PLSQL应该可以换个更好的递归算法的;二是没有滤重;反正最后的结果只是最简单的得到答案而已。
 
    具体的可以参见:
 
    http://www.itpub.net/viewthread.php?tid=1061129&extra=page%3D1%26amp%3Bfilter%3Ddigest&page=1
    http://www.itpub.net/viewthread.php?tid=1077244&extra=&page=1
 
 
 
create or replace function f_op (p_n1 number, p_op varchar2, p_n2 number) return number
as
begin
   return case when p_op = '+' then p_n1 + p_n2
               when p_op = '-' then p_n1 - p_n2
               when p_op = '*' then p_n1 * p_n2
               when p_op = '/' and p_n2<>0 then p_n1 / p_n2
               else null
          end;
end f_op;
/
 
 
create or replace procedure pro_24(p1 number, p2 number, p3 number, p4 number) as
  r_result number default 0;
begin
  for r in (
      with t_num as
          (select 1 id,p1 as n from dual
           union
           select 2 id,p2 as n from dual
           union
           select 3 id,p3 as n from dual
           union
           select 4 id,p4 as n from dual),
           t_op as
          (select '+' as o from dual
           union
           select '-' as o from dual
           union
           select '*' as o from dual
           union
           select '/' as o from dual)
       select distinct
              a.n  as a,
              o1.o as o1,
              b.n  as b,
              o2.o as o2,
              c.n  as c,
              o3.o as o3,
              d.n  as d
         from t_num a, t_num b, t_num c, t_num d,
              t_op  o1, t_op  o2, t_op  o3
        where a.id not in (b.id, c.id, d.id)
          and b.id not in (c.id, d.id)
          and c.id <> d.id) loop
 
       r_result := f_op(f_op(f_op(r.a,r.o1,r.b),r.o2,r.c),r.o3,r.d);
       if r_result between 23.9 and 24.1 then
       dbms_output.put_line('(('||r.a||r.o1||r.b||')'||r.o2||r.c||')'||r.o3||r.d);
       end if; --((a b) c) d
      
       r_result := f_op(f_op(r.a,r.o1,f_op(r.b,r.o2,r.c)),r.o3,r.d);
       if r_result between 23.9 and 24.1 then
       dbms_output.put_line('('||r.a||r.o1||'('||r.b||r.o2||r.c||'))'||r.o3||r.d);
       end if; --(a (b c)) d
      
       r_result := f_op(f_op(r.a,r.o1,r.b),r.o2,f_op(r.c,r.o3,r.d));
       if r_result between 23.9 and 24.1 then
       dbms_output.put_line('('||r.a||r.o1||r.b||')'||r.o2||'('||r.c||r.o3||r.d||')');
       end if; --(a b) (c d)
      
       r_result := f_op(r.a,r.o1,f_op(f_op(r.b,r.o2,r.c),r.o3,r.d));
       if r_result between 23.9 and 24.1 then
       dbms_output.put_line(r.a||r.o1||'(('||r.b||r.o2||r.c||')'||r.o3||r.d||')');
       end if; --a ((b c) d)
           
       r_result := f_op(r.a,r.o1,f_op(r.b,r.o2,f_op(r.c,r.o3,r.d)));
       if r_result between 23.9 and 24.1 then
       dbms_output.put_line(r.a||r.o1||'('||r.b||r.o2||'('||r.c||r.o3||r.d||'))');
       end if; --a (b (c d))
  end loop;
end;
/
 
 
exec pro_24(3,3,8,8);
 
posted on 2008-12-28 23:55 decode360 阅读(148) 评论(0)  编辑  收藏 所属分类: 06.PLSQL

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