Linked List

A Linked List is a data structure in which the objects are arranged in a linear order. Unlike Arrays, you cannot access any element directly through its index.

Topological Sort [Hackerearth]

A Topological sort of a Directed-Acyclic graph G is a linear ordering of all its vertices such that if G contains an edge E (u, v), then u appears before v in the ordering. And if the graph is not acyclic, then no linear ordering is possible.