Entropy Impurity

Compute the entropy, in bits, of a node from its class counts.

Implement solve(counts).

Returns. Return a non-negative float. Classes with zero count contribute nothing, and a node with no samples at all has entropy 0.0.

Examples

Example 1

Input:

solve([3, 1])

Output:

0.811278

Example 2

Input:

solve([2, 2])

Output:

1.0

Example 3

Input:

solve([4, 0])

Output:

0.0