2018-10-10 22:03:03 +00:00
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---
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id: 56533eb9ac21ba0edf2244e2
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2021-03-15 03:20:39 +00:00
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title: 凯撒密码
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2018-10-10 22:03:03 +00:00
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challengeType: 5
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2020-09-07 08:17:22 +00:00
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forumTopicId: 16003
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2021-01-13 02:31:00 +00:00
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dashedName: caesars-cipher
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2018-10-10 22:03:03 +00:00
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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2020-09-07 08:17:22 +00:00
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2021-03-15 03:20:39 +00:00
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凯撒密码( <dfn>Caesar cipher</dfn>)是最简单且最广为人知的密码(<dfn>ciphers</dfn>),也被称为移位密码(<dfn>shift cipher</dfn>)。 在移位密码中,明文中的字母通过按照一个固定数目进行偏移后被替换成新的字母。
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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[ROT13](https://en.wikipedia.org/wiki/ROT13) 是一个被广泛使用的加密技术,明文中的所有字母都被移动 13 位。 也就是, `A ↔ N`,`B ↔ O` 等等。
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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编写一个函数,它将 [ROT13](https://en.wikipedia.org/wiki/ROT13) 编码的字符串作为输入并返回解码字符串。
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2018-10-10 22:03:03 +00:00
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所有解码后的字母都必须为字母大写。 请不要解码非字母的字符(例如,空格、标点符号),但你需要在结果中保留它们。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --hints--
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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`rot13("SERR PBQR PNZC")` 应解码为 `FREE CODE CAMP`
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2018-10-10 22:03:03 +00:00
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```js
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assert(rot13('SERR PBQR PNZC') === 'FREE CODE CAMP');
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2018-10-10 22:03:03 +00:00
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```
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2021-03-15 03:20:39 +00:00
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`rot13("SERR CVMMN!")` 应解码为 `FREE PIZZA!`
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(rot13('SERR CVMMN!') === 'FREE PIZZA!');
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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`rot13("SERR YBIR?")` 应解码为 `FREE LOVE?`
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(rot13('SERR YBIR?') === 'FREE LOVE?');
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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`rot13("GUR DHVPX OEBJA SBK WHZCF BIRE GUR YNML QBT.")` 应解码为 `THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG.`
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2020-09-07 08:17:22 +00:00
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2018-10-10 22:03:03 +00:00
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```js
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assert(
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rot13('GUR DHVPX OEBJA SBK WHZCF BIRE GUR YNML QBT.') ===
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'THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG.'
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-08-13 15:24:35 +00:00
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2021-01-13 02:31:00 +00:00
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# --seed--
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## --seed-contents--
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```js
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function rot13(str) {
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return str;
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}
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rot13("SERR PBQR PNZC");
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```
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2020-12-16 07:37:30 +00:00
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# --solutions--
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2021-01-13 02:31:00 +00:00
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```js
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var lookup = {
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'A': 'N','B': 'O','C': 'P','D': 'Q',
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'E': 'R','F': 'S','G': 'T','H': 'U',
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'I': 'V','J': 'W','K': 'X','L': 'Y',
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'M': 'Z','N': 'A','O': 'B','P': 'C',
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'Q': 'D','R': 'E','S': 'F','T': 'G',
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'U': 'H','V': 'I','W': 'J','X': 'K',
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'Y': 'L','Z': 'M'
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};
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function rot13(encodedStr) {
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var codeArr = encodedStr.split(""); // String to Array
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var decodedArr = []; // Your Result goes here
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// Only change code below this line
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decodedArr = codeArr.map(function(letter) {
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if(lookup.hasOwnProperty(letter)) {
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letter = lookup[letter];
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}
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return letter;
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});
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// Only change code above this line
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return decodedArr.join(""); // Array to String
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}
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```
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