def partitionLabels(s: str) -> List[int]:
    answer = []
    end_position = last_position = 0
    memo = {char: index for index, char in enumerate(s)}

    for index, char in enumerate(s):
        end_position = max(end_position, memo[char])
        if index == end_position:
            answer.append(index-last_position+1)
            last_position = index + 1

    return answer