Isolation Path Length Factor

Problem

Compute the isolation forest path-length normalization c(n) = 2*H(n-1) - 2*(n-1)/n, where H(m) is the m-th harmonic number.

Return 0.0 for n <= 1.

Hint

c(n) normalizes the average path length of an unsuccessful search in a binary search tree.

case 1

in: [2]

expected: 1

case 2

in: [3]

expected: 1.6666666666666667

case 3

in: [5]

expected: 2.566666666666666

case 4

in: [1]

expected: 0

case 5

in: [0]

expected: 0

Starter codePython

def isolation_path_factor(n):
    # Your code here
    pass

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