問題描述：

  Given an array of characters, compress it in-place.

  The length after compression must always be smaller than or equal to the original array.

  Every element of the array should be a character (not int) of length 1.

  After you are done modifying the input array in-place, return the new length of the array.

Follow up:
  Could you solve it using only O(1) extra space?

Note:

  All characters have an ASCII value in [35, 126].
  1 <= len(chars) <= 1000.

程式碼：

class Solution {
    public int compress(char[] chars) {
        if(chars.length == 0) return 0; 

        int mark = 0;       
        int write
 
 = 0;
        for(int i = 0; i < chars.length; i++){
            if(i + 1 == chars.length || chars[i] != chars[i+1]){
                chars[write] = chars[mark];
                write++;
                if(mark < i){
                    for(char a : (""+(i-mark+1)).toCharArray())
                        chars[write
 
++] = a;
                }
                mark = i + 1;
            }
        }        
        return write;
    }
}