找工作-最长不重复字符

s = 'aaabbacccc'


def max_length_substring(s):
    item_list = []
    item_max = 0
    for i in s:
        if i not in item_list:
            item_list.append(i)
        else:
            if item_max < len(item_list):
                item_max = len(item_list)
            item_list = [i]

    if item_max < len(item_list):
        item_max = len(item_list)
    return item_max

print(max_length_substring(s))