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HomeDatabaseMysql Tutorial实现杨辉三角

实现杨辉三角

Jun 07, 2016 pm 02:56 PM
storageaccomplishat lastprocess

用存储过程和临时表来写,主要是想最后一个select出来结果,而且排成想要的三角形形状。 由于BIGINT数据的限制,最多可以显示67层。 结果 id ----------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- 1 1 2 1 1 3 1 2 1 4

       用存储过程和临时表来写,主要是想最后一个select出来结果,而且排成想要的三角形形状。        由于BIGINT数据的限制,最多可以显示67层。
结果
id                                                                                    
----------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
1                                              1                                 
2                                         1         1                            
3                                    1         2         1                       
4                               1         3         3         1                  
5                          1         4         6         4         1             
6                     1         5         10        10        5         1        
7                1         6         15        20        15        6         1   
8           1         7         21        35        35        21        7         1
CREATE proc #pr_YangHui
@c int
as
 /*    SQL实现显示杨辉三角    */
 /* 版本:   1.0              */
 /* 作者: Haiwer             */
 /* 版权所有                  */
 /* 2006.05.10               */
set nocount on
if @c<2 return        --两层以下就不排了
declare @i int
declare @j int
declare @sql varchar(8000)
declare @sql1 varchar(8000)
declare @sql2 varchar(8000)
create table #(id int IDENTITY(1,1),a50000 bigint)
insert #(a50000) values (1)   --第一层
set @i=2
while @i<=@c
begin
 --为了实现动态层,只好动态修改临时表结构
 set @sql='alter table # add a'+cast(50000+@i-1 as varchar(10))+' bigint,a'+cast(50000-@i+1 as varchar(10))+' bigint'  
 exec (@sql)
 set @sql1=''
 set @sql2=''
 set @j=@i-1
 while @j>=0
 begin
  --这里判断有点乱
  if @j=0
   set @sql1=@sql1+',a'+cast(50000-@j as varchar(10))
  else
   set @sql1=@sql1+',a'+cast(50000-@j as varchar(10))+',a'+cast(50000+@j as varchar(10))
  if @j=@i-1
   set @sql2=@sql2+',1,1'
  else
   if @j=0
    set @sql2=@sql2+',a'+cast(50000-@j-1 as varchar(10))+'+a'+cast(50000-@j+1 as varchar(10))
   else
    set @sql2=@sql2+',a'+cast(50000-@j-1 as varchar(10))+'+a'+cast(50000-@j+1 as varchar(10))+',a'+cast(50000+@j-1 as varchar(10))+'+a'+cast(50000+@j+1 as varchar(10))
  
  set @j=@j-2
 end
 --去掉多余的逗号
 set @sql1=right(@sql1,len(@sql1)-1)
 set @sql2=right(@sql2,len(@sql2)-1)
 set @sql=cast(@i-1 as varchar(10))
 exec('insert #('+@sql1+') select '+@sql2+' from # where id='+@sql)
 set @i=@i+1
end

set @i=50000-@c+1
set @j=50000+@c-1
set @sql=''
--去最长的数据,就是为了节省显示空间
select @sql1=CAST(len(cast(max(a50000) as varchar(50)))+1 AS VARCHAR(10)) from #
while @i<=@j
begin
 set @sql=@sql+',isnull(cast(a'+cast(@i as varchar(10))+' as varchar('+@sql1+')),'''')'
 set @i=@i+1
end
exec ('select id'+@sql+' from # order by id')
drop table #

GO
 
--调用
exec #pr_YangHui 8
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