{ "data": { "question": { "questionId": "757", "questionFrontendId": "756", "categoryTitle": "Algorithms", "boundTopicId": 1687, "title": "Pyramid Transition Matrix", "titleSlug": "pyramid-transition-matrix", "content": "
You are stacking blocks to form a pyramid. Each block has a color, which is represented by a single letter. Each row of blocks contains one less block than the row beneath it and is centered on top.
\n\nTo make the pyramid aesthetically pleasing, there are only specific triangular patterns that are allowed. A triangular pattern consists of a single block stacked on top of two blocks. The patterns are given as a list of three-letter strings allowed
, where the first two characters of a pattern represent the left and right bottom blocks respectively, and the third character is the top block.
"ABC"
represents a triangular pattern with a 'C'
block stacked on top of an 'A'
(left) and 'B'
(right) block. Note that this is different from "BAC"
where 'B'
is on the left bottom and 'A'
is on the right bottom.You start with a bottom row of blocks bottom
, given as a single string, that you must use as the base of the pyramid.
Given bottom
and allowed
, return true
if you can build the pyramid all the way to the top such that every triangular pattern in the pyramid is in allowed
, or false
otherwise.
\n
Example 1:
\n\n\nInput: bottom = "BCD", allowed = ["BCC","CDE","CEA","FFF"]\nOutput: true\nExplanation: The allowed triangular patterns are shown on the right.\nStarting from the bottom (level 3), we can build "CE" on level 2 and then build "A" on level 1.\nThere are three triangular patterns in the pyramid, which are "BCC", "CDE", and "CEA". All are allowed.\n\n\n
Example 2:
\n\n\nInput: bottom = "AAAA", allowed = ["AAB","AAC","BCD","BBE","DEF"]\nOutput: false\nExplanation: The allowed triangular patterns are shown on the right.\nStarting from the bottom (level 4), there are multiple ways to build level 3, but trying all the possibilites, you will get always stuck before building level 1.\n\n\n
\n
Constraints:
\n\n2 <= bottom.length <= 6
0 <= allowed.length <= 216
allowed[i].length == 3
{'A', 'B', 'C', 'D', 'E', 'F'}
.allowed
are unique.你正在把积木堆成金字塔。每个块都有一个颜色,用一个字母表示。每一行的块比它下面的行 少一个块 ,并且居中。
\n\n为了使金字塔美观,只有特定的 三角形图案 是允许的。一个三角形的图案由 两个块 和叠在上面的 单个块 组成。模式是以三个字母字符串的列表形式 allowed
给出的,其中模式的前两个字符分别表示左右底部块,第三个字符表示顶部块。
\"ABC\"
表示一个三角形图案,其中一个 “C”
块堆叠在一个 'A'
块(左)和一个 'B'
块(右)之上。请注意,这与 \"BAC\"
不同,\"B\"
在左下角,\"A\"
在右下角。你从底部的一排积木 bottom
开始,作为一个单一的字符串,你 必须 使用作为金字塔的底部。
在给定 bottom
和 allowed
的情况下,如果你能一直构建到金字塔顶部,使金字塔中的 每个三角形图案 都是允许的,则返回 true
,否则返回 false
。
\n\n
示例 1:
\n\n\n\n\n输入:bottom = \"BCD\", allowed = [\"BCC\",\"CDE\",\"CEA\",\"FFF\"]\n输出:true\n解释:允许的三角形模式显示在右边。\n从最底层(第3层)开始,我们可以在第2层构建“CE”,然后在第1层构建“E”。\n金字塔中有三种三角形图案,分别是“BCC”、“CDE”和“CEA”。都是允许的。\n\n\n
示例 2:
\n\n\n\n\n输入:bottom = \"AAAA\", allowed = [\"AAB\",\"AAC\",\"BCD\",\"BBE\",\"DEF\"]\n输出:false\n解释:允许的三角形模式显示在右边。\n从最底层(游戏邦注:即第4个关卡)开始,创造第3个关卡有多种方法,但如果尝试所有可能性,你便会在创造第1个关卡前陷入困境。\n\n\n
\n\n
提示:
\n\n2 <= bottom.length <= 6
0 <= allowed.length <= 216
allowed[i].length == 3
{'A', 'B', 'C', 'D', 'E', 'F', 'G'}
。allowed
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