Last week, we looked at a problem involving a subarray. A subarray is a *contiguous* sequence of elements from an array, meaning we can’t skip any elements when building the answer. A *subsequence*, on the other hand, allows us to skip elements, though the elements in the subsequence still need to stay in their original order.

LeetCode 300: Longest Increasing Subsequence says:

Given an integer array

`nums`

, return the length of the longest strictly increasing subsequence.

So we’re allowed to skip elements, but we can’t change the order of the elements, and for this problem, the elements in the solution must be strictly increasing.