You are given an integer array nums.

A prefix of nums is called sequential if each element in the prefix, starting from index $1$, is exactly $1$ greater than the element immediately preceding it. That is, a prefix nums[0..k] is sequential if nums[i] = nums[i - 1] + 1 for all $1 \leq i \leq k$. A prefix containing only a single element is always sequential.

Find the sum of the longest sequential prefix of nums. Let this sum be $S$.

Return the smallest integer $x$ such that $x \geq S$ and $x$ is not present in nums.

Constraints:

• $1 \leq$ nums.length $\leq 50$

• $1 \leq$ nums[i] $\leq 50$

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

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