Preparando MOJI
You are given an integer sequence $$$a_1, a_2, \dots, a_n$$$.
Find the number of pairs of indices $$$(l, r)$$$ ($$$1 \le l \le r \le n$$$) such that the value of median of $$$a_l, a_{l+1}, \dots, a_r$$$ is exactly the given number $$$m$$$.
The median of a sequence is the value of an element which is in the middle of the sequence after sorting it in non-decreasing order. If the length of the sequence is even, the left of two middle elements is used.
For example, if $$$a=[4, 2, 7, 5]$$$ then its median is $$$4$$$ since after sorting the sequence, it will look like $$$[2, 4, 5, 7]$$$ and the left of two middle elements is equal to $$$4$$$. The median of $$$[7, 1, 2, 9, 6]$$$ equals $$$6$$$ since after sorting, the value $$$6$$$ will be in the middle of the sequence.
Write a program to find the number of pairs of indices $$$(l, r)$$$ ($$$1 \le l \le r \le n$$$) such that the value of median of $$$a_l, a_{l+1}, \dots, a_r$$$ is exactly the given number $$$m$$$.
The first line contains integers $$$n$$$ and $$$m$$$ ($$$1 \le n,m \le 2\cdot10^5$$$) — the length of the given sequence and the required value of the median.
The second line contains an integer sequence $$$a_1, a_2, \dots, a_n$$$ ($$$1 \le a_i \le 2\cdot10^5$$$).
Print the required number.
5 4
1 4 5 60 4
8
3 1
1 1 1
6
15 2
1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
97
In the first example, the suitable pairs of indices are: $$$(1, 3)$$$, $$$(1, 4)$$$, $$$(1, 5)$$$, $$$(2, 2)$$$, $$$(2, 3)$$$, $$$(2, 5)$$$, $$$(4, 5)$$$ and $$$(5, 5)$$$.
Informação
Provedor Codeforces
Código CF1005E2
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Datas 09/05/2023 09:36:33
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