using System;
using System.Text;
/* ---------------------------------------------------------
Compress: turn "aaabbcccc" into "a3b2c4"
This is run-length encoding (RLE)
--------------------------------------------------------- */
class RLE
{
public static string Compress(string s)
{
if (string.IsNullOrEmpty(s))
return ""; // Edge case: empty string
StringBuilder outStr = new StringBuilder(); // Result string
int count = 1; // Count of repeated characters
// Start from index 1 and compare with previous character
for (int i = 1; i <= s.Length; i++) {
// If still repeating the same character, increase count
if (i < s.Length && s[i] == s[i - 1]) {
count++;
}
else {
// Character changed OR reached end of string
outStr.Append(s[i - 1]); // Add the character
outStr.Append(count); // Add how many times it repeated
count = 1; // Reset counter
}
}
return outStr.ToString();
}
/* ---------------------------------------------------------
Decompress: turn "a3b2c4" into "aaabbcccc"
Reads a letter, then reads digits, expands them.
--------------------------------------------------------- */
public static string Decompress(string s)
{
StringBuilder outStr = new StringBuilder(); // Result string
char currentChar = '\0'; // The character being processed
StringBuilder number = new StringBuilder(); // Digits representing the count
foreach (char c in s) {
if (char.IsLetter(c)) { // Found a letter
// If we already have a previous letter + number, expand it
if (currentChar != '\0' && number.Length > 0) {
int count = int.Parse(number.ToString());
outStr.Append(new string(currentChar, count));
}
currentChar = c; // Start new character
number.Clear(); // Reset number buffer
}
else if (char.IsDigit(c)) { // Found a digit
number.Append(c); // Build multi-digit number
}
}
// Handle the last character + number pair
if (currentChar != '\0' && number.Length > 0) {
int count = int.Parse(number.ToString());
outStr.Append(new string(currentChar, count));
}
return outStr.ToString();
}
static void Main()
{
string s = "wwwwwwwwwwwwbwwwwwwwwwwbbbwwwwwwccccwwwwwwwwwwww";
string c = Compress(s);
string d = Decompress(c);
Console.WriteLine("Original: " + s);
Console.WriteLine("Compressed: " + c);
Console.WriteLine("Decompressed: " + d);
}
}
/*
run:
Original: wwwwwwwwwwwwbwwwwwwwwwwbbbwwwwwwccccwwwwwwwwwwww
Compressed: w12b1w10b3w6c4w12
Decompressed: wwwwwwwwwwwwbwwwwwwwwwwbbbwwwwwwccccwwwwwwwwwwww
*/
