使用JS在Caesars Cypher中循环

Question

我已经花了很多时间试图解决这个问题，但我得出的结论是，经过几个小时的努力，我需要帮助。我知道非常接近，但无法摆脱单词之间的空格。这是我的代码：

function rot13(encodedStr) {
var codeArr = encodedStr.split("");
var decodedArr = []; 

var letters = ["A", "B", "C", "D", "E", "F","G", "H", "I", "J", "K", "L",      "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"];
var space = " ";
var location = 0;
var temp = [];
for(var i = 0; i<codeArr.length; i++){

if(letters[i] !== " "){
location = letters.indexOf(codeArr[i]);
decodedArr.push(letters[(location+13)%26]);

}else

decodedArr.push(letters[i]);
}

return decodedArr.join(""); 
}

rot13("SERR CVMMN!");

这应该返回“免费比萨饼！”

Answer 1

一些提示

卫生

让我们将所有字母标记为大写，以避免rot13('SERR CVMMN!');和rot13('SeRR cvMmn!');之间的歧义

var codeArr = encodedStr.toUpperCase().split(""); // sanitize input.

接下来让我们处理感叹号

应传递非字母字符。空间不是特例

if (/[A-Z]/.test(codeArr[i])) { // if the encoded character is an alphabet character
    // decode the character and push it on the decodedArr
} else {
    decodedArr.push(codeArr[i]); // let things like spaces and ! 
                                 // pass through to the output.
}

编码逻辑。

我认为你的逻辑有点倒退。而不是循环使用字母表为什么不循环编码文本并按顺序解码呢？

for (var i = 0; i < codeArr.length; i += 1) {
    if (/[A-Z]/.test(codeArr[i])) { // if the encoded character is an alphabet character
        // decode the character and push it on the decodedArr
        // the decoded character is 13 ahead of the current character in base 26.
        var ACode = 'A'.charCodeAt(); // 65
        var letter = codeArr[i];
        var letterCode = letter.charCodeAt() - ACode; // ASCII code
        letterCode = (letterCode + 13) % 26;
        decodedArr.push(letters[letterCode]);
    } else {
        decodedArr.push(codeArr[i]); // let things like spaces and ! 
                                     // pass through to the output.
    }
}