map 遍历,分类讨论,思维
若对 a [ i ] ( 1 < i < n ) a[i](1
a
[
i
]
<
a
[
i
+
1
]
a
n
d
a
[
i
]
<
a
[
i
−
1
]
a[i]a[i]
a
[
i
+
1
]
a
n
d
a
[
i
]
>
a
[
i
−
1
]
a[i]>a[i+1] and a[i]>a[i-1]
a[i]>a[i+1] and a[i]>a[i−1]:当b大于某个值时,会对 ans 贡献1
a
[
i
]
>
a
[
i
+
1
]
a
n
d
a
[
i
]
<
a
[
i
−
1
]
a[i]>a[i+1] and a[i]a[i]>a[i+1] and a[i]
a
[
i
−
1
]
a[i]a[i-1]
a[i]a[i−1]:同(3) 最后的贡献,就是“某个值”从小到大,贡献值的前缀和 每种情况的“某个值”,可以通过画图或举例来求出具体如何表示#include



