#coding interview question
1) Write a program for run-length encoding
for eg:  AAABBCCCCC
is written as 3A2B5C
String RLE(String input)
{
if String.IsNullOrEmpty(input) return input;
int count = 0;
int prevChar = '/0';
StringBuilder output = "";
for (int i =0; i < input.Length; i++)
{
if (input[i] != prevChar){
       if (prevChar != '/0') {
            output += count.toString();
            output += prevChar;
        }
      count = 1;
      prevChar = input[i];
}else{
      count+=1;
} // end if
} // end for
            output += count.toString();
            output += prevChar;
return output;
}

2) And in place encoding is as follows:
<work-in-progress>
Void RLE(ref StringBuilder input)
{
if String.IsNullOrEmpty(input.toString ()) return;

int count = 0;
int prev = -1; // previous index
int prevCount = 0;
Char prevChar = '/0';
String readOnlyCopy = input.SubString(0,1); // just the first bRead to get started
int countLen = count.ToString().Length;
int i = 0; // index to span reading the length of the string
bool readAhead = false;
while ( i < input.Length && readOnlyCopy.Length > 0)
{
  if (prev == -1 || input[i] != input[prev] ){
       if (prev != -1) {
            prevChar = input [prev];
            prevCount = count;
            countLen = count.toString().Length;  // actually we need fixed size packing say 4 bytes for number and one byte for char but the processing is similar
            if (countLen  >= count){
             readOnlyCopy += input.subString (i+1, countLen); // to include count and char
             readAhead = true;
            }

            Int w = prev;
            If (prev==-1) w++;
            If (countLen > input.Length - i ) input.resize (input.Length×2);
            For (int j=0; j < countLen; j++){
                   Input[w]=count.toString ()[j];
                   w++;
             }
             Input [w] = prevChar;
             // i = i + countLen;
             readOnlyCopy.TrimLeft(0, countLen);

        }
      count = 1;
      prev = i;
      prevChar = input [prev];
      Countlen=1;
}else{
      count+=1;
} // end if
i++;
if (readahead == false)
      readOnlyCopy += input.SubString(i, 1); // next bRead
else
      readahead=false;
} // end while
// one last while lookahead
            int w = prev;
            if (w + count.toString().Length + 2 > input.Length) input.resize(input.Length *2 );
            countLen = count.toString().Length;
            for (int j = 0; j < countLen; j++){
                  Input[w] = count.toString()[j];
                  w++;
            }
            Input[w] = prevChar;
            I =  i + countLen;
            w++;
            Input[w] = '/0';
return ;
}