longest-alternating-subarray-after-removing-at-most-one-element

java

python3

python

javascript

typescript

csharp

golang

kotlin

swift

rust

ruby

dart

scala

elixir

erlang

racket

bash

mysql

mssql

postgresql

oraclesql

pythondata

Algorithms

You are given an integer array <code>nums</code>.

A subarray <code>nums[l..r]</code> is alternating if one of the following holds:

<ul>
	<li><code>nums[l] &lt; nums[l + 1] &gt; nums[l + 2] &lt; nums[l + 3] &gt; ...</code></li>
	<li><code>nums[l] &gt; nums[l + 1] &lt; nums[l + 2] &gt; nums[l + 3] &lt; ...</code></li>
</ul>

In other words, if we compare adjacent elements in the subarray, then the comparisons alternate between strictly greater and strictly smaller.

You can remove at most one element from <code>nums</code>. Then, you select an alternating subarray from <code>nums</code>.

Return an integer denoting the maximum length of the alternating subarray you can select.

A subarray of length 1 is considered alternating.

&nbsp;
Example 1:

<div class="example-block">
Input: nums = [2,1,3,2]

Output: 4

Explanation:

<ul>
	<li>Choose not to remove elements.</li>
	<li>Select the entire array <code>[2, 1, 3, 2]</code>, which is alternating because <code>2 &gt; 1 &lt; 3 &gt; 2</code>.</li>
</ul>
</div>

Example 2:

<div class="example-block">
Input: nums = [3,2,1,2,3,2,1]

Output: 4

Explanation:

<ul>
	<li>Choose to remove <code>nums[3]</code> i.e., <code>[3, 2, 1, 2, 3, 2, 1]</code>. The array becomes <code>[3, 2, 1, 3, 2, 1]</code>.</li>
	<li>Select the subarray <code>[3, 2, 1, 3, 2, 1]</code>.</li>
</ul>
</div>

Example 3:

<div class="example-block">
Input: nums = [100000,100000]

Output: 1

Explanation:

<ul>
	<li>Choose not to remove elements.</li>
	<li>Select the subarray <code>[100000, 100000]</code>.</li>
</ul>
</div>

&nbsp;
Constraints:

<ul>
	<li><code>2 &lt;= nums.length &lt;= 105</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 105</code></li>
</ul>