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203 lines
4.9 KiB
Markdown
203 lines
4.9 KiB
Markdown
---
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id: 59e0a8df964e4540d5abe599
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title: 执行脑 ****
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challengeType: 1
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forumTopicId: 302261
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dashedName: execute-brain
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---
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# --description--
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Write a function to implement a Brain\*\*\*\* interpreter. The function will take a string as a parameter and should return a string as the output. More details are given below:
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RCBF is a set of <a href="https://rosettacode.org/wiki/Brainf***" target="_blank" rel="noopener noreferrer nofollow">Brainf\*\*\*</a> compilers and interpreters written for Rosetta Code in a variety of languages.
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以下是每个 RCBF 版本的链接。
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一个实现只需要正确地实现以下指令：
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| Command | 描述 |
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| ------------------------- | ---------------------------------------------- |
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| <code>></code> | Move the pointer to the right |
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| <code><</code> | 向左移动指针 |
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| <code>+</code> | 递增指针下的存储单元 |
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| <code>-</code> | 递减指针下的存储单元 |
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| <code>.</code> | 输出指针所在存储单元所代表的字符 |
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| <code>,</code> | 输入一个字符并将其存储在指针所在的存储单元中 |
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| <code>\[</code> | 如果指针下的存储单元为 0，则跳过匹配的 <code>]</code> |
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| <code>]</code> | 如果指针下的存储单元非 0，则跳回匹配的 <code>\[</code> |
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允许任何单元格大小，EOF (*E*nd-*O*-*F*ile) 支持是可选的，就像你有有界或无界内存一样。
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# --hints--
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`brain(bye)` 应该返回一个字符串
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```js
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assert(typeof brain(bye) === 'string');
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```
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`brain("++++++[>++++++++++<-]>+++++.")` should return "A"
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```js
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assert.equal(brain('++++++[>++++++++++<-]>+++++.'), 'A');
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```
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`brain(bye)` 应该返回 `Goodbye, World!\r\n`
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```js
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assert.equal(brain(bye), 'Goodbye, World!\r\n');
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```
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`brain(hello)` 应该返回 `Hello World!\n`
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```js
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assert.equal(brain(hello), 'Hello World!\n');
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```
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`brain(fib)` 应该返回 `1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89`
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```js
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assert.equal(brain(fib), '1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89');
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```
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# --seed--
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## --before-user-code--
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```js
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let fib=`+
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++
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+++
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++++
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+>+>>
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>>++++
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+++++++
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++++++++
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+++++++++
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++++++++++
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++++++>++++
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++++++++++++
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+++++++++++++
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+++<<<<<<[>[>>
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>>>>+>+<<<<<<<-
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]>>>>>>>[<<<<<<<
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+>>>>>>>-]<[>++++
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++++++[-<-[>>+>+<<
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<-]>>>[<<<+>>>-]+<[
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>[-]<[-]]>[<<[>>>+<<
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<-]>>[-]]<<]>>>[>>+>+
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<<<-]>>>[<<<+>>>-]+<[>
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[-]<[-]]>[<<+>>[-]]<<<<
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<<<]>>>>>[++++++++++++++
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+++++++++++++++++++++++++
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+++++++++.[-]]++++++++++<[
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->-<]>+++++++++++++++++++++
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+++++++++++++++++++++++++++.
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[-]<<<<<<<<<<<<[>>>+>+<<<<-]>
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>>>[<<<<+>>>>-]<-[>>.>.<<<[-]]
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<<[>>+>+<<<-]>>>[<<<+>>>-]<<[<+
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>-]>[<+>-]<<<-]`;
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let hello='++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.'
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let bye='++++++++++[>+>+++>++++>+++++++>++++++++>+++++++++>++++++++++>+++++++++++>++++++++++++<<<<<<<<<-]>>>>+.>>>>+..<.<++++++++.>>>+.<<+.<<<<++++.<++.>>>+++++++.>>>.+++.<+++++++.--------.<<<<<+.<+++.---.';
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```
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## --seed-contents--
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```js
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function brain(prog) {
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}
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```
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# --solutions--
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```js
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function brain(prog){
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var output="";
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var code; // formatted code
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var ip = 0; // current instruction within code
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var nest = 0; // current bracket nesting (for Out button)
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var ahead = []; // locations of matching brackets
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var data = [0]; // data array (mod by +, -)
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var dp = 0; // index into data (mod by <, >)
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var inp = 0; // current input character (fetch with ,)
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var quit = 0;
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var commands = {
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'>':function() { if (++dp >= data.length) data[dp]=0 },
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'<':function() { if (--dp < 0) quit++ },
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'+':function() { ++data[dp] },
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'-':function() { --data[dp] },
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'[':function() { if (!data[dp]) ip = ahead[ip]; else ++nest },
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']':function() { if ( data[dp]) ip = ahead[ip]; else --nest },
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',':function() {
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var c = document.getElementById("input").value.charCodeAt(inp++);
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data[dp] = isNaN(c) ? 0 : c; // EOF: other options are -1 or no change
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},
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'.':function() {
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output+=String.fromCharCode(data[dp]);
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/*var s = document.getElementById("output").innerHTML)
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+ String.fromCharCode(data[dp]);
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s = s.replace(/\n/g,"<br>").replace(/ /g,"&nbsp;");
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document.getElementById("output").innerHTML = s;*/
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},
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};
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let ar=prog.split('');
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var st = [], back, error = -1;
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for (ip=0; ip<ar.length; ip++) {
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switch(ar[ip]) {
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case '[':
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st.push(ip);
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break;
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case ']':
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if (st.length == 0) error = ip;
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back = st.pop();
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ahead[ip] = back;
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ahead[back] = ip;
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break;
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}
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}
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for(ip=0;ip<ar.length;ip++){
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if(commands.hasOwnProperty(ar[ip]))
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commands[ar[ip]]();
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}
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return output;
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}
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```
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