ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
269 lines
7.5 KiB
Markdown
269 lines
7.5 KiB
Markdown
---
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id: 59e09e6d412c5939baa02d16
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title: 执行马尔可夫算法
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challengeType: 5
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videoUrl: ''
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dashedName: execute-a-markov-algorithm
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---
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# --description--
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任务：
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为[马尔可夫算法](<https://en.wikipedia.org/wiki/Markov algorithm> "wp：马尔可夫算法")创建解释器。
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规则的语法如下：
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<pre>[ruleset] ::= (([comment] | [rule]) [newline]+)*
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[comment] ::= # {[any character]}
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[rule] ::= [pattern] [whitespace] -> [whitespace] [.] [replacement]
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[whitespace] ::= ([tab] | [space]) [[whitespace]]
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</pre>
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每行有一条规则。
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如果在 \[replacement] 之前有一个 `.`（句点），那么这就是一个终止规则。在这种情况下，解释器必须停止执行。
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规则集由一系列规则组成，可能包含一些注释。
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规则集
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我们会对你提交的代码进行如下测试：
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**规则集 1：**
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<pre># 此条规则来自 Wikipedia：
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# <code>http://en.wikipedia.org/wiki/Markov_Algorithm</code>
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A -> apple
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B -> bag
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S -> shop
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T -> the
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the shop -> my brother
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(终止规则) -> .
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</pre>
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对于这段文本：
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`I bought a B of As from T S.`
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应该输出：
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`I bought a bag of apples from my brother.`
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**规则集 2：**
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终止规则的测试
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<pre># 基于 Wikipedia 的规则稍做修改
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A -> apple
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B -> bag
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S -> .shop
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T -> the
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the shop -> my brother
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(终止规则) -> .
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</pre>
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对于这段文本：
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`I bought a B of As from T S.`
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应该输出：
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`I bought a bag of apples from T shop.`
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**规则集 3：**
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这条不仅可以用来测试替换顺序是否正确，还可以测试你的代码中对正则表达式的处理是否完备。如果你的代码没有对正则表达式进行正确的转义处理，那在替换的时候就会出现问题。
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<pre># BNF Syntax testing rules
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A -> apple
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WWWW -> with
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Bgage -> ->.*
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B -> bag
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->.* -> money
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W -> WW
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S -> .shop
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T -> the
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the shop -> my brother
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(终止规则) -> .
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</pre>
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对于这段文本：
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`I bought a B of As W my Bgage from T S.`
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应该输出：
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`I bought a bag of apples with my money from T shop.`
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**规则集 4：**
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这条是用来测试规则扫描的顺序是否正确，并可能捕获以错误顺序扫描的替换例程。这里我们选取了通用的一元乘法引擎（请注意，在此实现中，输入的表达式必须放在两个下划线之间）。
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<pre> ##一元乘法引擎，用于测试马尔可夫算法实现
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### by Donal Fellows
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# 一元加法引擎
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_+1 -> _1+
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1+1 -> 11+
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# 将乘法转换为普通加法
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1! -> !1
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,! -> !+
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_! -> _
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# 一元乘法，左侧为被乘数，右侧为乘数
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1*1 -> x,@y
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1x -> xX
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X, -> 1,1
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X1 -> 1X
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_x -> _X
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,x -> ,X
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y1 -> 1y
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y_ -> _
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# 下一阶段
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1@1 -> x,@y
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1@_ -> @_
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,@_ -> !_
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++ -> +
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# 加法的终止条件
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_1 -> 1
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1+_ -> 1
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_+_ ->
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</pre>
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对于这段文本：
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`_1111*11111_`
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应该输出：
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`11111111111111111111`
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**规则集5：**
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一台简单的[图灵机](http://en.wikipedia.org/wiki/Turing_machine)包含三个状态的["忙碌海狸"](http://en.wikipedia.org/wiki/Busy_beaver)。纸带由 0 和 1 组成，状态为 A、B、C 和代表终止（Halt）的 H。通过在字符前写状态字母来的方式来指示读写头的位置。机器运行时需要的初始纸带必须通过输入在一开始全部给出。
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这一规则集除了可以证明 Markov 算法是图灵完备的，它还帮我找出了使用 C++ 完成此题中的一个错误，而且这个错误没有被前四个规则集抓到。
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<pre># 图灵机：三个状态的"忙碌海狸"
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# 状态 A，符号 0 => 写入 1，向右移动，新状态 B
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A0 -> 1B
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# 状态 A，符号 1 => 写入 1，向左移动，新状态 C
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0A1 -> C01
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1A1 -> C11
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# 状态 B，符号 0 => 写入 1，向左移动，新状态 A
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0B0 -> A01
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1B0 -> A11
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# 状态 B，符号 1 => 写入 1，向右移动，新状态 B
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B1 - > 1B
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# 状态 C，符号 0 => 写入 1，向左移动，新状态 B
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0C0 - > B01
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1C0 - > B11
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# 状态 C，符号 1 => 写入 1，向左移动，停止
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0C1 - > H01
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1C1 - > H11
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</pre>
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这个规则集应将这段输入：
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`000000A000000`
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转换成：
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`00011H1111000`
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# --hints--
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`markov` 应是一个函数。
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```js
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assert(typeof markov === 'function');
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```
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`markov(["A -> apple","B -> bag","S -> shop","T -> the","the shop -> my brother","a never used -> .terminating rule"],"I bought a B of As from T S.")` 应返回 "I bought a bag of apples from my brother."。
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```js
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assert.deepEqual(markov(rules[0], tests[0]), outputs[0]);
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```
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`markov(["A -> apple","B -> bag","S -> .shop","T -> the","the shop -> my brother","a never used -> .terminating rule"],"I bought a B of As from T S.")` 应返回 "I bought a bag of apples from T shop."。
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```js
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assert.deepEqual(markov(rules[1], tests[1]), outputs[1]);
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```
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`markov(["A -> apple","WWWW -> with","Bgage -> ->.*","B -> bag","->.* -> money","W -> WW","S -> .shop","T -> the","the shop -> my brother","a never used -> .terminating rule"],"I bought a B of As W my Bgage from T S.")` 应返回 "I bought a bag of apples with my money from T shop."。
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```js
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assert.deepEqual(markov(rules[2], tests[2]), outputs[2]);
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```
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`markov(["_+1 -> _1+","1+1 -> 11+","1! -> !1",",! -> !+","_! -> _","1*1 -> x,@y","1x -> xX","X, -> 1,1","X1 -> 1X","_x -> _X",",x -> ,X","y1 -> 1y","y_ -> _","1@1 -> x,@y","1@_ -> @_",",@_ -> !_","++ -> +","_1 -> 1","1+_ -> 1","_+_ -> "],"_1111*11111_")` 应返回 "11111111111111111111"。
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```js
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assert.deepEqual(markov(rules[3], tests[3]), outputs[3]);
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```
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`markov(["A0 -> 1B","0A1 -> C01","1A1 -> C11","0B0 -> A01","1B0 -> A11","B1 -> 1B","0C0 -> B01","1C0 -> B11","0C1 -> H01","1C1 -> H11"],"")` 应返回 "00011H1111000"。
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```js
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assert.deepEqual(markov(rules[4], tests[4]), outputs[4]);
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```
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# --seed--
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## --seed-contents--
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```js
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function markov(rules,test) {
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}
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```
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# --solutions--
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```js
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function markov(rules,test) {
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let pattern = new RegExp("^([^#]*?)\\s+->\\s+(\\.?)(.*)");
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let origTest = test;
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let captures = [];
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rules.forEach(function(rule){
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let m = pattern.exec(rule);
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for (let j = 0; j < m.length; j++)
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m[j] = m[j + 1];
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captures.push(m);
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});
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test = origTest;
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let copy = test;
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for (let j = 0; j < captures.length; j++) {
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let c = captures[j];
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test = test.replace(c[0], c[2]);
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if (c[1]==".")
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break;
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if (test!=copy) {
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j = -1;
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copy = test;
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}
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}
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return test;
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}
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// tail:
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let rules=[["A -> apple","B -> bag","S -> shop","T -> the","the shop -> my brother","a never used -> .terminating rule"],
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["A -> apple","B -> bag","S -> .shop","T -> the","the shop -> my brother","a never used -> .terminating rule"],
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["A -> apple","WWWW -> with","Bgage -> ->.*","B -> bag","->.* -> money","W -> WW","S -> .shop","T -> the","the shop -> my brother","a never used -> .terminating rule"],
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["_+1 -> _1+","1+1 -> 11+","1! -> !1",",! -> !+","_! -> _","1*1 -> x,@y","1x -> xX","X, -> 1,1","X1 -> 1X","_x -> _X",",x -> ,X","y1 -> 1y","y_ -> _","1@1 -> x,@y","1@_ -> @_",",@_ -> !_","++ -> +","_1 -> 1","1+_ -> 1","_+_ -> "],
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["A0 -> 1B","0A1 -> C01","1A1 -> C11","0B0 -> A01","1B0 -> A11","B1 -> 1B","0C0 -> B01","1C0 -> B11","0C1 -> H01","1C1 -> H11"]];
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let tests=["I bought a B of As from T S.",
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"I bought a B of As from T S.",
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"I bought a B of As W my Bgage from T S.",
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"_1111*11111_",
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"000000A000000"];
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let outputs=["I bought a bag of apples from my brother.",
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"I bought a bag of apples from T shop.",
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"I bought a bag of apples with my money from T shop.",
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"11111111111111111111",
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"00011H1111000"];
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```
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