PUZZLEUP 2015

solomon_007

newkid 发表于 2015-9-19 08:47
转了个金牛座！

谢谢

lastwinner

lugionline 发表于 2015-9-17 15:52
AAAB是可以涵盖AAAA的情况的

这个显然不对，比方 BAAA 可以被 AAAA覆盖，但是不能被 AAAB覆盖

下面newkid理解对了，我没说BAAA和AAAB可以相互覆盖

cszxheap

newkid 发表于 2015-9-17 23:11
给你发个章，要哪个？

我的思路和你一样，经过分析后C只能够是4位。我先求出所有四位以下的数，用BITA ...

SELECT a.n a,b.n b,c.n c FROM d2 a,d4 b,d4 c WHERE a.n+b.n=c.n AND BITAND(a.bit,b.bit)=0 AND BITAND(a.bit+b.bit,c.bit)=0
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前面的做法基本相同，写到这里的bitand我的顺序有不同，随手写成BITAND(b.bit,c.bit)=0 AND BITAND(b.bit+c.bit,a.bit)=0
结果奇慢无比
难道是前者计划里将两位数集合的谓词尽早发生作用降低了成本，从而引发了hash替代了nestloop？

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能不用函数就不用

newkid

cszxheap 发表于 2015-9-22 18:44
SELECT a.n a,b.n b,c.n c FROM d2 a,d4 b,d4 c WHERE a.n+b.n=c.n AND BITAND(a.bit,b.bit)=0 AND BITAN ...

计划不一样了，从HASH JOIN变成了NESTED LOOPS。但也不至于那么慢啊。百思不得其解。

改写成下面这样也很快：


WITH d AS (SELECT LEVEL-1 d,POWER(2,LEVEL-1) bit FROM DUAL CONNECT BY LEVEL<=10)
,num(len,n,bit) AS (
SELECT 1,d ,bit FROM d WHERE d<>0
UNION ALL
SELECT len+1,to_number(n||d),num.bit+d.bit FROM num,d WHERE BITAND(num.bit,d.bit)=0 AND len<4
)
,d2 AS (SELECT n,bit FROM num WHERE len=2)
,d3 AS (SELECT n,bit FROM num WHERE len=3)
,d4 AS (SELECT n,bit FROM num WHERE len=4)
SELECT a.n a,b.n b,c.n c FROM d3 a,d3 b,d4 c WHERE a.n<b.n AND a.n+b.n=c.n AND a.bit+b.bit+c.bit=power(2,10)-1
UNION ALL
SELECT a.n a,b.n b,c.n c FROM d2 a,d4 b,d4 c WHERE a.n+b.n=c.n AND a.bit+b.bit+c.bit=power(2,10)-1
ORDER BY c;

newkid

#9:




CUBE TRAVEL

You will make a travel through the edges of two cubes connected by their vertices as shown in the figure.

-You will start on A, and finish on B.

-You can pass through the vertices more than once except the finishing vertex B.
-You can't pass through the edges more than once.

In how many different ways can this travel be done?

Note: Two travels having same edges in different order will be considered as different.

你将沿着两个立方体的边进行遍历，这两个立方体通过顶点连接，如图所示，

起点在A，终点是B

除了终点B之外，其他的顶点你可以通过不止一次。
你不能通过同一条边多于一次。

总共有几种不同的遍历方法？

注：如果两种方法经过的边是相同的，但是顺序不同，那么它们被认为是两种不同的方法。
------------
这个用SQL应该没什么问题。

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newkid 发表于 2015-9-23 23:14
#9:

都必须通过连接点

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把顶点标号，然后直接连的边放在表的一行

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newkid 发表于 2015-9-23 23:14
#9:

A也能多次通过吗

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with t as
(select 'a' p1,'c' p2 , 'ac' l from dual union all
...
)