Water-Filling Level Update

Problem

Perform one water-filling update. Given noise variances, the current water level and the target total power, count the active channels with n_i < level, compute the used power sum(max(0, level - n_i)), and return level + (target_power - used) / active. Return the level unchanged when no channel is active.

Hint

If the used power already matches the target, the level does not move.

Test cases

case 1

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

expected: 2

case 2

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

expected: 0

case 3

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

expected: 5

case 4

in: [[1,3],0.5,1]

expected: 0.5

Starter codePython

def water_filling_update(noise_vars, level, target_power):
    # Your code here
    pass

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