分类： 赛事动态

A tortoise and a hare are going to race against each other on the track shown below.一只乌龟和一只野兔将在下面所示的赛道上进行赛跑。

Beavers love to play a game called "Strawberry Hunt."海狸们喜欢玩一个叫做“草莓狩猎”的游戏。

Rules: 规则:

1. A different number of strawberries is put on each area of a field.在一块田地的不同区域放置了数量不等的草莓。
2. Starting from any field, take 3 steps.从任何一块田地开始，走三步。
3. Each step can be one of:每一步都可以是以下之一：
   • move up one area 向上移动一个区域
   • move down one area 向下移动一个区域
   • move right one area 向右移动一个区域
   • move left one area 向左移动一个区域
4. Eat all the strawberries you found.把你找到的所有草莓都吃掉。

Examples:例子:

Choosing the path on the left, a beaver will eat 9 + 1 + 6 + 5 = 21 strawberries.

Choosing the path on the right, the beaver will eat  7 + 1 + 5 + 8 = 21  strawberries as well. 

选择左边的路，一只海狸会吃掉 9 + 1 + 6 + 5 = 21 个草莓。选择右边的路，海狸也会吃掉  7 + 1 + 5 + 8 = 21  个草莓。

Little Beaver is playing on this grid:小海狸正在这个网格上玩耍：

Question:

How many strawberries can Little Beaver eat at most?小海狸最多能吃多少颗草莓？

 

 

 

 

 

Explanation 解释

Answer: 答案:23

Explanation: 解释:

Though there are 51 possible ways to finish the game (see table below), we don't have to check all 51 total sums of strawberries. Here is how:

尽管完成游戏有 51 种可能的方式（见下表），但我们不必检查所有 51 种草莓的总和。方法如下：

We know that each player can reach 4 areas that in their short path. These paths can only make the following shapes:

我们知道每个玩家在其短路径中可以到达 4 个区域。这些路径只能形成以下形状：

Now, we check these shapes including any of the areas with 9 or 8 strawberries (including all shapes with both of these areas). Since checking field combinations with 9 or 8 strawberries will also cover those fields with 5, 6 or 7 strawberries, all grids with larger numbers of strawberries will be covered. Then, we can find the largest total number of strawberries:

现在，我们检查这些形状，包括任何有 9 个或 8 个草莓的区域（包括所有同时具有这两种区域的形状）。由于检查有 9 个或 8 个草莓的田地组合也会涵盖那些有 5 个、6 个或 7 个草莓的田地，所以所有草莓数量更多的格子都会被涵盖。然后，我们就能找到草莓总数的最大值：

Now, note that without the areas with 8 and 9 strawberries, the maximum sum of strawberries on any other combination of four areas is 7 + 6 + 5 + 5 = 23. That is, also without areas 8 and 9, 23 cannot be exceeded. Therefore, Little Beaver can eat at most 23 strawberries.

现在请注意，如果没有 8 个和 9 个草莓的区域，那么其他任意四个区域的草莓总数最大为 7 + 6 + 5 + 5 = 23 个。也就是说，即便没有 8 个和 9 个草莓的区域，总数也无法超过 23 个。因此，小海狸最多能吃 23 个草莓。

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（Bebras每日一练部分展示）

The beavers are painting pictures, made of different shapes, on a computer.海狸们正在电脑上绘制由不同形状组成的图画。

They can paint any shape by selecting one of four colors and then clicking on the shape.他们可以通过选择四种颜色中的一种，然后点击形状来给任何形状上色。

Example:例子：

The beavers could paint the 'face'  completely blue with just two moves: 海狸只需两步就能把“脸”完全涂成蓝色：

1. Select yellow, paint the red part to get: 选择黄色，将红色部分涂成黄色得到：
2. Then select blue, paint the yellow part to get: 然后选择蓝色，将黄色部分涂成蓝色，得到：

Task 任务:

Make the pattern below completely green with the fewest number of moves possible.

(Press 'Save' when you have finished.)（完成后请按“保存”。）用尽可能少的步数将下面的图案全部涂成绿色。

 

 

 

 

 

Explanation 解释

Ana is playing the game "pick-up sticks."安娜正在玩“捡棍子”的游戏。

She drops some sticks on a table and then picks them all up following these rules:她把一些木棍放在桌子上，然后按照以下规则把它们全部捡起来：

- You may pick up one stick at a time;你可以一次捡一根棍子；

- You may pick up a stick only if it is on top: no other stick may be covering it.只有当某根木棍在最上面，即没有其他木棍压在它上面时，你才可以把它捡起来。

Example:例子:

3 sticks are dropped and look like this. Press play to see how Ana picks them up in order:三根棍子掉落下来，排列成这样。点击播放，看看安娜是如何依次捡起它们的：

 

 

Question:问题：

Ana dropped 6 sticks like this:安娜像这样扔下了 6 根木棍：

 

 

 

 

 

Explanation 解释

Monica and Michael brought necklaces back from their vacation.莫妮卡和迈克尔度假回来时带回了项链。

Monica's necklace: 莫妮卡的项链:

Michael's necklace: 迈克尔的项链:

They each took several pearls off of their own necklace to make a new necklace for their friend Anastasia. Now their necklaces look like this. 他们各自从自己的项链上取下几颗珍珠，为他们的朋友安娜斯塔西娅做了一条新项链。现在他们的项链是这个样子。

Question:问题：

What does Anastasia's necklace look like?安纳斯塔西娅的项链是什么样子的？

 

 

 

 

 

Explanation 解释

Answer: 答案:

Monica's necklace is missing three violet pearls and Michael's is missing three red pearls, and that is exactly what is in this necklace.

莫妮卡的项链少了三颗紫珍珠，迈克尔的项链少了三颗红珍珠，而这串项链上恰好就有这些。is not correct because it contains four violet pearls. Monika’s necklace started with five violet pearls and she now has two left, so the maximum number that can be on Anastasija’s necklace is three.

这是不正确的，因为这条项链上有四颗紫珍珠。莫妮卡的项链起初有五颗紫珍珠，现在还剩两颗，所以安纳斯塔西娅的项链上最多只能有三颗。

is not correct because it contains blue and green pearls. All the green and blue pearls remain on Monika's and Michael's necklaces, so Anastasija’s necklace cannot have any green or blue pearls.

这是不正确的，因为其中包含蓝色和绿色的珍珠。所有绿色和蓝色的珍珠都还在莫妮卡和迈克尔的项链上，所以安娜斯塔西娅的项链上不能有任何绿色或蓝色的珍珠。

For the same reason, answer  is not correct.

出于同样的原因，这个答案不正确。

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（Bebras每日一练部分展示）

Brian’s favorite candies come in five flavors. Brian puts one of each flavor into a tube to take to school. During the day, Brian eats the candies in the order they come out of the top of the tube. Today he wants to eat them in the following order: , , , , .

布莱恩最喜欢的糖果有五种口味。布莱恩把每种口味的一颗糖果放进一个管子里带去学校。白天，布莱恩按照糖果从管子顶部出来的顺序吃糖果。今天他想按照以下顺序吃：   。

Question 问题

Pack Brian’s tube for him so that he gets the candies in the preferred order.把布赖恩的管子给他装好，这样他就能按喜欢的顺序吃到糖果了。

(Drag the candies into the tube and press 'Save' when complete.)（将糖果拖入管中，完成后按“保存”。）

 

 

 

 

 

Explanation 解释

For the candies to come out of the tube in the preferred order, it is important to understand that the first one in will be the last one out. This means that the tube of sweets needs to be filled like this:为了让糖果按照理想的顺序从管子里出来，重要的是要明白先进入管子的糖果会最后出来。这意味着装糖果的管子需要这样装填：

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（Bebras每日一练部分展示）

Buffy has a pile of six clean shirts on her bed. She wants to put them away in her four drawers.巴菲在床上放着一堆六件干净的衬衫。她想把它们收进她的四个抽屉里。

She takes one shirt at a time from the pile and puts it into a drawer. Buffy starts with the top drawer, then uses the second from the top, and works her way down. When she has put a shirt into the bottom drawer, she starts again from the top.她每次从那堆衬衫里拿一件放进抽屉里。布菲从最上面的抽屉开始，接着用从上往下数第二个抽屉，然后依次往下放。当她把一件衬衫放进最下面的抽屉后，又从最上面的抽屉开始放。

 

 

 

 

 

 

 

 

Three children often borrow books from the library.三个孩子经常从图书馆借书。

The librarian wants to know which book has been borrowed most often. 图书管理员想知道哪本书被借阅的次数最多。

She uses the shapes on each child's library card to make a list of who borrowed which book.她根据每个孩子借书证上的形状来列出谁借了哪本书。

Task: 任务:

Look at her list in the middle. Which book was borrowed most often?看看中间她的清单。哪本书借阅次数最多？

(Click on the correct book on the right and press 'Save.')（点击右侧正确的书本，然后按“保存”。）

 

 

 

 

 

Explanation 解释

Task: 任务:

Paint the picture below. 请画出下面这幅画。

Painting Rules:绘画规则:

1. No part of the picture may be left white.1. 画面中任何部分都不许留白。

2. Parts that are touching cannot be the same color. For example, the leaf and the background may not both be green.2. 相接触的部分不能是相同的颜色。例如，叶子和背景不能都是绿色的。

Painting instructions:绘画说明：

Click on a paint color to choose it.点击一种油漆颜色以选择它。

Click on a part of the picture (like the background) to paint it.点击图片的某一部分（比如背景）来给它上色。

There is more than one way to correctly color the picture.给这幅画上色的方法不止一种。

Press 'Save' when you are finished.完成后请按“保存”。

 

 

 

 

Explanation 解释

Answer: 答:There are many possible answers, here is one:答案有很多，这里给出一个：Explanation: 解释:

The main rule in this task is: No painted areas that are next to each other are allowed to have the same colour.此任务的主要规则是：相邻的涂色区域不允许使用相同的颜色。

Start by chosing one of the three paints and paint the centre of the flower.首先从三种颜料中选择一种，给花朵的中心上色。

Next choose a different colour and paint the corner petals with it. They do not touch each other so can be the same colour.接下来选择一种不同的颜色，用它来给角落的花瓣上色。这些花瓣彼此不接触，所以可以是同一种颜色。

Next choose the third paint and colour in the remaining four petals. These also do not touch each other.接下来选择第三种颜料，给剩下的四片花瓣上色。这些花瓣之间也不要相互接触。

The middle of the flowerhead touches all the petals so must be a differnet colour to all the petals. The same applies to the background so this must be the same colour as the centre of the flower.花心部分与所有花瓣相接，所以颜色必须与所有花瓣不同。背景也是如此，所以其颜色必须与花心相同。

Finally, colour the stem and leaf while still obeying the main task rule.最后，给茎和叶上色，同时仍要遵循主要任务规则。

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（Bebras每日一练部分展示）

2015年Bebras挑战练习题

Senior (16-18岁) 集合

名称	类型
Beaver Tutorials（海狸教程）	A
You Won't Find It（你不会找到的）	A
Drawing Stars（画星星）	A
Stack Computer（堆栈的电脑）	A
E-mail Scam（电子邮件诈骗）	A
Popularity（流行）	B
Beaver the Alchemist（炼金术士海狸）	B
Fireworks（烟花）	B
Bowl Factory（碗的工厂）	B
Word Chains（文字链）	B
Kangaroo（袋鼠）	C
Spies（间谍）	C
Mobiles（手机）	C
Pirate Hunters（海盗猎人）	C
Building a chip（构建芯片）	C

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（Bebras每日一练部分展示）