Line Graph Degree Sequence

Problem

Compute the degree of every edge when edges become nodes of the line graph.

In a simple undirected graph, an edge u-v is adjacent in the line graph to every other edge at u or at v, so its degree is deg(u) + deg(v) - 2. Return the degrees in input edge order. n is the number of original nodes and edges is a list of [u, v] pairs.

Hint

Subtracting 2 removes the edge itself, counted once at each endpoint.

Test cases

case 1

in: [4,[[0,1],[1,2],[2,3]]]

expected: [1,2,1]

case 2

in: [4,[[0,1],[0,2],[0,3]]]

expected: [2,2,2]

case 3

in: [3,[[0,1],[1,2],[2,0]]]

expected: [2,2,2]

case 4

in: [2,[[0,1]]]

expected: [0]

Starter codePython

def line_graph_degree_sequence(n, edges):
    # Your code here
    pass

4 test cases · run your code against them in the editor