message: Update string-compression.py
diff: # Time: O(n)
  # Space: O(1)
  +# 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?
  +#
  +# Example 1:
  +# Input:
  +# ["a","a","b","b","c","c","c"]
  +#
  +# Output:
  +# Return 6, and the first 6 characters of the input array should be: ["a","2","b","2","c","3"]
  +#
  +# Explanation:
  +# "aa" is replaced by "a2". "bb" is replaced by "b2". "ccc" is replaced by "c3".
  +# Example 2:
  +# Input:
  +# ["a"]
  +#
  +# Output:
  +# Return 1, and the first 1 characters of the input array should be: ["a"]
  +#
  +# Explanation:
  +# Nothing is replaced.
  +# Example 3:
  +# Input:
  +# ["a","b","b","b","b","b","b","b","b","b","b","b","b"]
  +#
  +# Output:
  +# Return 4, and the first 4 characters of the input array should be: ["a","b","1","2"].
  +#
  +# Explanation:
  +# Since the character "a" does not repeat, it is not compressed. "bbbbbbbbbbbb" is replaced by "b12".
  +# Notice each digit has it's own entry in the array.
  +# Note:
  +# All characters have an ASCII value in [35, 126].
  +# 1 <= len(chars) <= 1000.
  +
  class Solution(object):
  def compress(self, chars):
  """
  :type chars: List[str]
  :rtype: int
  """
  - i, j = 0, 0
  - while j < len(chars):
  - if j+1 == len(chars) or chars[j] != chars[j+1]:
  - chars[i] = chars[j]
  - i += 1
  - j += 1
  - else:
  - k = j
  - while j < len(chars) and chars[j] == chars[k]:
  - j += 1
  - chars[i] = chars[k]
  - i += 1
  - n, left = j-k, i
  + anchor, write = 0, 0
  + for read, c in enumerate(chars):
  + if read+1 == len(chars) or chars[read+1] != c:
  + chars[write] = chars[anchor]
  + write += 1
  + if read > anchor:
  + n, left = read-anchor+1, write
  while n > 0:
  - chars[i] = chr(n%10+ord('0'))
  + chars[write] = chr(n%10+ord('0'))
  + write += 1
  n /= 10
  - i += 1
  - right = i-1
  + right = write-1
  while left < right:
  chars[left], chars[right] = chars[right], chars[left]
  left += 1
  right -= 1
  - return i
  + anchor = read+1
  + return write
  