<p>There are <code>n</code> soldiers standing in a line. Each soldier is assigned a <strong>unique</strong> <code>rating</code> value.</p>

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

<ul>
	<li>Choose 3 soldiers with index (<code>i</code>, <code>j</code>, <code>k</code>) with rating (<code>rating[i]</code>, <code>rating[j]</code>, <code>rating[k]</code>).</li>
	<li>A team is valid if: (<code>rating[i] &lt; rating[j] &lt; rating[k]</code>) or (<code>rating[i] &gt; rating[j] &gt; rating[k]</code>) where (<code>0 &lt;= i &lt; j &lt; k &lt; n</code>).</li>
</ul>

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

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

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

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> rating = [2,1,3]
<strong>Output:</strong> 0
<strong>Explanation:</strong> We can&#39;t form any team given the conditions.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> rating = [1,2,3,4]
<strong>Output:</strong> 4
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>n == rating.length</code></li>
	<li><code>3 &lt;= n &lt;= 1000</code></li>
	<li><code>1 &lt;= rating[i] &lt;= 10<sup>5</sup></code></li>
	<li>All the integers in <code>rating</code> are <strong>unique</strong>.</li>
</ul>

MAX_SIZE = 3

class Solution:
    def numTeams(self, rating: List[int]) -> int:
        return solve(rating)

def solve(nums):
    n = len(nums)
    incCache = [[None] * (MAX_SIZE + 1) for _ in range(n)]
    decCache = [[None] * (MAX_SIZE + 1) for _ in range(n)]
    ans = 0
    
    for i in range(n):
        ans += countTeams(nums, i, 1, incCache)

    nums.reverse()

    for i in range(n):
        ans += countTeams(nums, i, 1, decCache)

    return ans

def countTeams(nums, i, size, cache):
    n = len(nums)

    if i == n: return 0
    if size == 3: return 1
    if cache[i][size] != None: return cache[i][size]
    
    ans = 0
    
    for j in range(i + 1, n):
        if nums[j] > nums[i]:
            ans += countTeams(nums, j, size + 1, cache)

    cache[i][size] = ans
    return ans
16300