You are given a string
s. We want to partition the string into as many parts as possible so that each letter appears in at most one part.
Return a list of integers representing the size of these parts.
Input: s = "ababcbacadefegdehijhklij" Output: [9,7,8] Explanation: The partition is "ababcbaca", "defegde", "hijhklij". This is a partition so that each letter appears in at most one part. A partition like "ababcbacadefegde", "hijhklij" is incorrect, because it splits s into less parts.
Input: s = "eccbbbbdec" Output: 
1 <= s.length <= 500
sconsists of lowercase English letters.