#
# 
# @param arr int整型一维数组 the array
# @return int整型
#
class Solution:
    def maxLength(self , arr ):
        # write code here
        '''
        # 方法一:队列
        Max, queue = 0, []
        for n in arr:
            while n in queue:
                queue.pop(0)
            queue.append(n)
            Max = max(len(queue), Max)
        return Max
        '''
        # 方法二:滑动窗口
        j, Max, seen = 0, 0, set()
        for i in range(len(arr)):
            while j < len(arr) and arr[j] not in seen:
                seen.add(arr[j])
                j += 1
            Max = max(Max, j-i) # 发现重复的,统计最大长度
            seen.remove(arr[i]) # 删除重复的元素
        return Max