种树

fzy · 发表于 2005-4-4 18:38:57

1. 10棵树种成5行，每行4棵，怎么种？ (Difficulty: +)

2. 11棵树种成6行，每行4棵，怎么种？ (Difficulty: ++)

3. 12棵树种成7行，每行4棵，怎么种？ (Difficulty: ++)

4. 13棵树种成9行，每行4棵，怎么种？ (Difficulty: +++)

fzy · 发表于 2005-4-6 23:42:13

I know. They probably didn't notice it either.

怀疑1 · 发表于 2005-4-6 22:36:41

You are right. I did not notice this problem. It seems that only two people at WXC tried, and these two guys are not among the best there.

fzy · 发表于 2005-4-6 21:43:52

http://web.wenxuecity.com/BBSView.php?SubID=netiq&MsgID=30918

怀疑1 · 发表于 2005-4-6 21:35:17

I am also in WXC but did not see this problem

fzy · 发表于 2005-4-6 19:29:56

Recently problem 4 appeared at WXC, with a ranking similar to the following:

6 rows : High School
7 rows : Bachelor
8 rows : Master
9 rows : Ph.D

Nice to see some Ph.D's here . There is only one Master and some Bachelors at WXC.

yma16 · 发表于 2005-4-6 00:29:07

回复：you are right.

fzy · 发表于 2005-4-5 18:30:26

The two answers for No. 4 (as well as my own answer) are structually the same. I solved it this way: Start with one line and two points on the line. Draw three other lines from each point. These six lines intersect and form a " 田字". Adjust the "田字" so that its two diagonals intersect the original line.

As far as I know, 9 is the best known result for 13 trees. The exact upper bound is still unknown, that is, no one proved it is not possible to have 10 rows, and no one did it either.

欢歌角度 · 发表于 2005-4-5 07:20:39

和前面的是一样的

sean9991 · 发表于 2005-4-5 07:13:39

怀疑 · 发表于 2005-4-5 02:38:47

First draw four lines.

怀疑 · 发表于 2005-4-5 02:33:26

怀疑 · 发表于 2005-4-5 02:20:13

I got an answer for No. 4

sean9991 · 发表于 2005-4-4 23:20:56

isn't that 15 trees?

sean9991 · 发表于 2005-4-4 23:19:52

sean9991 · 发表于 2005-4-4 23:17:52

2 and 3

yma16 · 发表于 2005-4-4 22:56:19

a a a a
a a a a
a a a a
a a a

新用户 · 发表于 2005-4-4 22:21:14

就是在五角星焦点处种树，5条线就是5行，每行4颗。

		自动登录	找回密码
密码			立即注册

动态微博

种树

I know. They probably didn't notice it either.

回复：回复：I am also in WXC but did not see this proble

回复：I am also in WXC but did not see this problem

I am also in WXC but did not see this problem

ranking

回复：you are right.

Well done

和前面的是一样的

answer for 4（图）

回复：回复：I got an answer for No. 4（图）

回复：I got an answer for No. 4（图）

I got an answer for No. 4

isn't that 15 trees?

answer for 2 and 3（图）

2 and 3

回复：11棵树种成6行，每行4棵

挑个简单的，我来回答第一题