Wedge Count

Problem

Count the wedges of an undirected graph: unordered pairs of edges that share a center, including wedges whose endpoints are also connected.

A node of degree d contributes d * (d - 1) / 2 wedges, so sum that over all nodes. edges is a list of [u, v] pairs.

Hint

Wedge count relates to degrees by the handshake-style identity sum of d choose 2.

case 1

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

expected: 3

case 2

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

expected: 2

case 3

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

expected: 3

case 4

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

expected: 12

Starter codePython

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

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