Hi Everyone,\n\nI will try to explain the concept and some important observations related to the concept of Subsequence for anyone who may find it useful.\n\n**What are Subsequences?**\n\nWe can answer that by understanding the **difference between Subarray, Subsequence and Subset**\n\n* A **subarray is a contiguous part of array and maintains relative ordering of elements**. For an array/string of size n, there are n*(n+1)/2 non-empty subarrays/substrings.\n\n* A **subsequence maintain relative ordering of elements but may or may not be a contiguous part of an array**. For a sequence of size n, we can have 2^n-1 non-empty sub-sequences in total.\n\n* A **subset MAY NOT maintain relative ordering of elements and can or cannot be a contiguous part of an array**. For a set of size n, we can have (2^n) sub-sets in total.\n\nLet us understand it with an example.\n\nConsider an array:\n\narray = [1,2,3,4]\n\n* Subarray : [1,2],[1,2,3] - is continous and maintains relative order of elements\n\n* Subsequence: [1,2,4] - is not continous but maintains relative order of elements\n\n* Subset: [1,3,2] - is not continous and does not maintain relative order of elements\n\n**Some interesting observations** :\n\n* Every Subarray is a Subsequence.\n* Every Subsequence is a Subset.

Hi Everyone,\n\nI will try to explain the concept and some important observations related to the concept of Subsequence for anyone who may find it useful.\n\nWh