1395. Count Number of Teams

https://leetcode.com/problems/count-number-of-teams

Description

There are n soldiers standing in a line. Each soldier is assigned a unique rating value.

You have to form a team of 3 soldiers amongst them under the following rules:

• Choose 3 soldiers with index (i, j, k) with rating (rating[i], rating[j], rating[k]).

• A team is valid if: (rating[i] < rating[j] < rating[k]) or (rating[i] > rating[j] > rating[k]) where (0 <= i < j < k < n).

Return the number of teams you can form given the conditions. (soldiers can be part of multiple teams).

Example 1:

**Input:** rating = [2,5,3,4,1]
**Output:** 3
**Explanation:** We can form three teams given the conditions. (2,3,4), (5,4,1), (5,3,1). 

Example 2:

**Input:** rating = [2,1,3]
**Output:** 0
**Explanation:** We can't form any team given the conditions.

Example 3:

**Input:** rating = [1,2,3,4]
**Output:** 4

Constraints:

• n == rating.length

• 3 <= n <= 1000

• 1 <= rating[i] <= 105

• All the integers in rating are unique.

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