Java 游程长度编码

Question

游程编码采用重复出现字符的字符串，例如 qqqqqWWWWr，并将其转换为 5q4Wr。重复出现的字符前面应标明该字符连续出现的次数。如果它只连续出现一次，则前面不应带有数字。

这是我到目前为止所拥有的，但我似乎无法让它正常工作:

public class Compress {

    public static void main(String[] args) {
        System.out.print("Enter a string: ");
        String s = IO.readString();

        int currentRunLength = 1;
        String compressedString = "";

        for (int i = 0; i < s.length(); i++) {
            if (i == s.length() - 1){
                if (currentRunLength == 1) {
                compressedString += s.charAt(i);
                break;
                } else {
                compressedString += currentRunLength + s.charAt(i);
                break;
                }
            }
            if (s.charAt(i) == s.charAt(i + 1)) {
                currentRunLength++;
            }
            if (s.charAt(i) != s.charAt(i + 1) && currentRunLength > 1) {
                compressedString += currentRunLength + s.charAt(i);
                currentRunLength = 1;
            }
            if (s.charAt(i) != s.charAt(i + 1) && currentRunLength == 1) {
                compressedString += s.charAt(i);
            }
        }
        IO.outputStringAnswer(compressedString);
    }
}

运行示例

输入字符串:qqqqWWWr

结果:“117q90Wr”

Answer 1

当算法是众所周知的时候，也许你不应该重新发明轮子。我在 Rosetta Code 上找到了一个实现，网址如下:http://rosettacode.org/wiki/Run-length_encoding#Java

重新粘贴以防原始 URL 被删除:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RunLengthEncoding {
    public static String encode(String source) {
        StringBuffer dest = new StringBuffer();
        for (int i = 0; i < source.length(); i++) {
            int runLength = 1;
            while (i+1 < source.length() && source.charAt(i) == source.charAt(i+1)) {
                runLength++;
                i++;
            }
            dest.append(runLength);
            dest.append(source.charAt(i));
        }
        return dest.toString();
    }

    public static String decode(String source) {
        StringBuffer dest = new StringBuffer();
        Pattern pattern = Pattern.compile("[0-9]+|[a-zA-Z]");
        Matcher matcher = pattern.matcher(source);
        while (matcher.find()) {
            int number = Integer.parseInt(matcher.group());
            matcher.find();
            while (number-- != 0) {
                dest.append(matcher.group());
            }
        }
        return dest.toString();
    }

    public static void main(String[] args) {
        String example = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW";
        System.out.println(encode(example));
        System.out.println(decode("1W1B1W1B1W1B1W1B1W1B1W1B1W1B"));
    }
}