an array of pointers storing the head nodes of the linked lists
let arr = new Array ( k ) ; arr [ 0 ] = new Node ( 1 ) ; arr [ 0 ] . next = new Node ( 3 ) ; arr [ 0 ] . next . next = new Node ( 5 ) ; arr [ 0 ] . next . next . next = new Node ( 7 ) ; arr [ 1 ] = new Node ( 2 ) ; arr [ 1 ] . next = new Node ( 4 ) ; arr [ 1 ] . next . next = new Node ( 6 ) ; arr [ 1 ] . next . next . next = new Node ( 8 ) ; arr [ 2 ] = new Node ( 0 ) ; arr [ 2 ] . next = new Node ( 9 ) ; arr [ 2 ] . next . next = new Node ( 10 ) ; arr [ 2 ] . next . next . next = new Node ( 11 ) ;