Run-length decompression

Question

CS student here. I want to write a program that will decompress a string that has been encoded according to a modified form of run-length encoding (which I\'ve already written c

Answer 1

A simple regex will do.

final Matcher m = Pattern.compile("(\\D)(\\d+)").matcher(input);
final StringBuffer b = new StringBuffer();
while (m.find()) 
  m.appendReplacement(b, replicate(m.group(1), Integer.parseInt(m.group(2))));
m.appendTail(b);

where replicate is

String replicate(String s, int count) {
  final StringBuilder b = new StringBuilder(count);
  for (int i = 0; i < count; i++) b.append(s);
  return b.toString();
}