Apportion.swift

func apportion(quota: Int, _ population: [Int]) -> [Int] {    
    var portions = population.map({ $0 / quota })
    let errors = population.map({ $0 % quota })
    
    let adjustments = (errors.reduce(0, +) + quota / 2) / quota
    errors
        .enumerated()
        .sorted(by: { $0.element > $1.element })
        .prefix(adjustments)
        .forEach {
            portions[$0.offset] += 1
        }

    return portions
}

print(apportion(quota: 100, [125, 25, 45])) // -> [1, 0, 1]
print(apportion(quota: 1000, [5555, 1110])) // -> [6, 1]
print(apportion(quota: 10, [1, 109]))       // -> [0, 11]
print(apportion(quota: 100, [33, 33, 33]))  // -> [1, 0, 0]