Algoexpert Run-Length Encoding.java

	import java.util.*;
	class Program {
	// O(n) T | O(n) S
	public String runLengthEncoding(String string) {
	// handle corner cases
	if (string == null || string.length() == 0) {
	return string;
	}
	int currentRunLength = 1;
	StringBuilder encodedStringCharacters = new StringBuilder();
	for (int i = 1; i < string.length(); i++) {
	char previousChar = string.charAt(i - 1);
	char currentChar = string.charAt(i);
	if ((currentChar != previousChar) || (currentRunLength == 9)) {
	encodedStringCharacters.append(currentRunLength);
	encodedStringCharacters.append(previousChar);
	currentRunLength = 1;
	} else {
	currentRunLength++;
	}
	}
	// handle the last run
	if (currentRunLength > 0) {
	encodedStringCharacters.append(currentRunLength);
	encodedStringCharacters.append(string.charAt(string.length() - 1));
	}
	return encodedStringCharacters.toString();
	}
	}

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