Maximum Profitable Triplets With Increasing Prices I
<p>Given the <strong>0-indexed</strong> arrays <code>prices</code> and <code>profits</code> of length <code>n</code>. There are <code>n</code> items in an store where the <code>i<sup>th</sup></code> item has a price of <code>prices[i]</code> and a profit of <code>profits[i]</code>.</p>

<p>We have to pick three items with the following condition:</p>

<ul>
	<li><code>prices[i] &lt; prices[j] &lt; prices[k]</code> where <code>i &lt; j &lt; k</code>.</li>
</ul>

<p>If we pick items with indices <code>i</code>, <code>j</code> and <code>k</code> satisfying the above condition, the profit would be <code>profits[i] + profits[j] + profits[k]</code>.</p>

<p>Return<em> the <strong>maximum profit</strong> we can get, and </em><code>-1</code><em> if it&#39;s not possible to pick three items with the given condition.</em></p>

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

<pre>
<strong>Input:</strong> prices = [10,2,3,4], profits = [100,2,7,10]
<strong>Output:</strong> 19
<strong>Explanation:</strong> We can&#39;t pick the item with index i=0 since there are no indices j and k such that the condition holds.
So the only triplet we can pick, are the items with indices 1, 2 and 3 and it&#39;s a valid pick since prices[1] &lt; prices[2] &lt; prices[3].
The answer would be sum of their profits which is 2 + 7 + 10 = 19.</pre>

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

<pre>
<strong>Input:</strong> prices = [1,2,3,4,5], profits = [1,5,3,4,6]
<strong>Output:</strong> 15
<strong>Explanation:</strong> We can select any triplet of items since for each triplet of indices i, j and k such that i &lt; j &lt; k, the condition holds.
Therefore the maximum profit we can get would be the 3 most profitable items which are indices 1, 3 and 4.
The answer would be sum of their profits which is 5 + 4 + 6 = 15.</pre>

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

<pre>
<strong>Input:</strong> prices = [4,3,2,1], profits = [33,20,19,87]
<strong>Output:</strong> -1
<strong>Explanation:</strong> We can&#39;t select any triplet of indices such that the condition holds, so we return -1.
</pre>

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

<ul>
	<li><code>3 &lt;= prices.length == profits.length &lt;= 2000</code></li>
	<li><code>1 &lt;= prices[i] &lt;= 10<sup>6</sup></code></li>
	<li><code>1 &lt;= profits[i] &lt;= 10<sup>6</sup></code></li>
</ul>
Binary Indexed Tree; Segment Tree; Array
func maxProfit(prices []int, profits []int) int {
	n := len(prices)
	ans := -1
	for j, x := range profits {
		left, right := 0, 0
		for i := 0; i < j; i++ {
			if prices[i] < prices[j] {
				left = max(left, profits[i])
			}
		}
		for k := j + 1; k < n; k++ {
			if prices[j] < prices[k] {
				right = max(right, profits[k])
			}
		}
		if left > 0 && right > 0 {
			ans = max(ans, left+x+right)
		}
	}
	return ans
}