G(n,p) Expected Edges

Problem

The Erdos-Renyi random graph G(n, p) has each of the C(n, 2) possible edges present independently with probability p. Return the expected number of edges:

E[edges] = C(n, 2) * p.

Return 0.0 for negative n.

Hint

Sum the edge-indicator expectations.

Test cases

case 1

in: [10,0.5]

expected: 22.5

case 2

in: [5,0.1]

expected: 1

case 3

in: [1,0.9]

expected: 0

case 4

in: [0,0.5]

expected: 0

Starter codePython

def gn_p_expected_edges(n, p):
    # Your code here
    pass

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