count-integers-appearing-in-a-single-block

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Algorithms

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

An integer <code>x</code> is special if all occurrences of <code>x</code> in <code>nums</code> appear in a single contiguous block.

Return the number of distinct special integers in <code>nums</code>.

&nbsp;
Example 1:

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

Output: 1

Explanation:

<ul>
	<li>1 appears at indices 0 and 3, forming two separate blocks, so it is not special.</li>
	<li>2 appears in a single contiguous block at indices <code>[1, 2]</code>, so it is special.</li>
</ul>

Therefore, there is one special integer.
</div>

Example 2:

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

Output: 2

Explanation:

<ul>
	<li>3 appears in a single contiguous block at indices <code>[0, 1]</code>, so it is special.</li>
	<li>1 appears at indices 2 and 5, forming two separate blocks, so it is not special.</li>
	<li>2 appears in a single contiguous block at indices <code>[3, 4]</code>, so it is special.</li>
</ul>

Therefore, there are two special integers.
</div>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
</ul>