2022 AMC 12A 第 7 题

先试着解答 2022 AMC 12A 第 7 题,然后核对你的答案与精心整理的解答,解答来自 LIVE by Po-Shen Loh。你也可以参加完整限时模拟考试、查看全部 2022 AMC 12A 解答,或核对答案。

所有题目均经美国数学协会(MAA)官方合法授权使用。

7.

一个长方形如图被分成 55 个区域。每个区域要涂成一种纯色,可选颜色为红、橙、黄、蓝、绿。相接触的区域必须涂成不同颜色,颜色可以重复使用。共有多少种不同的涂色方法?
A rectangle is partitioned into 55 regions as shown. Each region is to be painted a solid color - red, orange, yellow, blue, or green - so that regions that touch are painted different colors, and colors can be used more than once. How many different colorings are possible?
120120
270270
360360
540540
720720
答案:D
知识点:图论乘法原理
小提示:
先给与最多其他区域相邻的区域涂色
Color the region that borders the most others first
大提示:
有一个区域与另外四个区域都相邻;其余每个区域都必须避开两个已经使用的颜色
One region touches all four others; each remaining region must avoid two already-used colors
解答:
底部中间的区域与其他四个区域都共边。先给它涂色,有 55 种方法。
左上区域与它相邻,有 44 种选择。其余三个区域各与两个已经涂好的区域相邻,而这两个区域颜色不同,所以各有 33 种选择。
总数为 5⋅4⋅3⋅3⋅3=5405\cdot4\cdot3\cdot3\cdot3=540。
因此,正确答案是 D。
The bottom-middle region shares a border with all four other regions. Color it first in 55 ways.
The top-left region borders it, giving 44 choices. Each of the three remaining regions borders exactly two already-colored regions, which have different colors, leaving 33 choices apiece.
The total is 5⋅4⋅3⋅3⋅3=540.5\cdot4\cdot3\cdot3\cdot3=540.
Thus, the correct answer is D.
LIVE by Po-Shen Loh
LIVE项目

LIVE直播课程

Self-Paced录播课程

启明星Star计划

奖学金项目

关于我们

罗博深是谁?

邮件联系

订阅英文简报

加入我们

申请明星导师

For a more Thought Full world.

© 2026 Expii, Inc.