The problem statement is incorrect. It should sound like:

"We are given a "graph" in the form of a 2D-array, with distinct values for each node.

In the given 2D-array, each element [u, v] represents an edge between nodes v and u.

We can remove exactly one edge in this "graph" to make the graph acyclic, i.e. such that no 2 nodes have more than one path between them."