python 代码

n = int(input())
a = list(map(int,input().split()))
cnt = [0] * 100010
l,r = 0,0
res,s = 0,0
while r < n:
    if cnt[a[r]] == 0:
        s = s + 1
    cnt[a[r]] += 1
    while s > 2:
        cnt[a[l]] -= 1
        if cnt[a[l]] == 0:
            s = s - 1
        l = l + 1
    res = max(res,r-l+1)
    r = r + 1
print(res)        
# ----------------------------------超时-------------------------------------------------#
# n = int(input())
# a = list(map(int,input().split()))
# l,r = 0,1 # 左右指针
# res = 1 # 存储答案
# cnt = 1 # 记录当前长度
# maxc = a[l] # 初始化当前最大值
# minc = a[l] # 初始化当前最小值
# while r < n: # 保证不越界
#     maxc = max(maxc,a[r]) # 计算目前最大值
#     minc = min(minc,a[r]) # 计算目前最小值
#     if maxc - minc <= 1: # 判断是否满足第二个约束条件
#         cnt = cnt + 1 #满足所有条件，当前右指针元素合法
#         r = r + 1 # 右指针右移
#     else: # 不满足第二个约束条件
#         l = l + 1 # 左指针右移，尝试减小极差
#         maxc = max(a[l:r + 1])
#         minc = min(a[l:r + 1])
#         cnt = cnt - 1
#     res = max(cnt,res)
# print(res)