Minimize Rounding Error to Meet Target

lcpy gen -n 1058   # by problem number
lcpy gen -s minimize_rounding_error_to_meet_target   # by problem name

Input: prices = ["0.700","2.800","4.900"], target = 8
Output: "1.000"
Explanation: Use Floor, Ceil and Ceil operations to get (0.7 - 0) + (3 - 2.8) + (5 - 4.9) = 0.7 + 0.2 + 0.1 = 1.0.

Input: prices = ["1.500","2.500","3.500"], target = 10
Output: "-1"
Explanation: It is impossible to meet the target.

Input: prices = ["1.500","2.500","3.500"], target = 9
Output: "1.500"

from decimal import Decimal


class Solution:
    # Time: O(n log n)
    # Space: O(n)
    def minimize_error(self, prices: list[str], target: int) -> str:
        floor_sum = 0
        fracs: list[Decimal] = []
        for p in prices:
            d = Decimal(p)
            floor_sum += int(d)
            if frac := d - int(d):
                fracs.append(frac)
        if not floor_sum <= target <= floor_sum + len(fracs):
            return "-1"
        ceils = target - floor_sum
        fracs.sort(reverse=True)
        error = ceils - sum(fracs[:ceils]) + sum(fracs[ceils:])
        return f"{error:.3f}"