Given an undirected graph G = (V, E), for any subset of nodes S ⊆ V we can
construct a graph Gs from G by removing all nodes in S together with their
incident edges. In the critical node problem (CNP), we are given an integer
1 ≤ k ≤ |V | and need to find a subset S of size k such that the graph
Scan first array check repeated values as in example( rt_triangle(4, {0,
-1, -1, 1}, {1, -2, 1, -2}))
-1,-1 is repeated twice at indices in array respectively 1and 2.
now in second y-axis array check values at indices given by first array (in
above example these values are -2 and 1 respectively)
