javascript

Question

对于我的作业，我正在编写代码来压缩然后通过javascript中的无损压缩解压缩字符串。

例如 -
原文字符串：heeeeelllllloo
压缩：h1e5l6o2
解压缩：heeeeelllllloo

此代码以无限循环形式出现，问题出现在压缩函数中。请帮我找/解决问题！
这就是我到目前为止所做的：

// Read in the original text
var textToCompress = prompt("Enter the text you would like to compress: ");
runLengthEncoding(textToCompress);

function runLengthEncoding(originalText){
console.log("Original Text: " + originalText);
console.log("");

// Compress the text
console.log("COMPRESSING...");

var compressedText = compress(originalText);
console.log("Compressed: " + compressedText);
console.log("");

//Decompress the text
console.log("DECOMPRESSING...");

//var decompressedText = decompress(compressedText);
console.log("Decompressed: " + decompressedText);
console.log("");

// Make sure the compression was lossless
if(originalText == decompressedText)
{
    console.log("Success! The decompressed text is the same as the original!");
}
}

// Compresses the original String by building up a new String
// with each character and how many times it repeats in a given run.
// Returns the compressed text.
function compress(original){
  var result = "";
  //Write your code here
  for (var i = 1; i < original.length; i++){//look at each character in string
    var sum = 1;
    var currentChar = original.charAt(i);
    //if currentchar is the first character
    if (currentChar == original.charAt(0)){//isolate frist character of the string
      result = currentChar;//add the currentchar to result
      console.log(result);
    //if currentchar is not the first character
    } else if (currentChar !== original.charAt(0)) {
      //if currentchar is equal to the previous character
      if (currentChar == original.charAt(i-1)){
        sum++;
    } else {
        result += sum;//add sum ot the result and reset sum to 1
        sum = 1;
        i = 0;
      }

}
}
}

// Decompresses the compressed Run Length Encoded text back
// into the original form.
function decompress(compressedText)
{
var result = "";

for(var i = 0; i < compressedText.length; i += 2)
{
    // Get the current run character
    var character = compressedText.charAt(i);

    // Get the run length
    var runLength = parseInt(compressedText.charAt(i+1));

    // Add that many repetitions of the original character to the result
    for(var runIndex = 0; runIndex < runLength; runIndex++)
    {
        result += character;
    }
}

return result;
}

Answer 1

首先，不要比较字符以找出这个字符是否是第一个字符，因为如果在文本中重复第一个字符，这将返回true。

我看到的一件事是，每当你找到一个新的字符时，你就将索引i设置为0，这会导致你的函数再次从字符串的开头开始，并以死锁结束。

至少我的想法，我希望我可以帮助你