1058. Minimize Rounding Error to Meet Target

https://leetcode.com/problems/minimize-rounding-error-to-meet-target

Description

Given an array of prices [p1,p2...,pn] and a target, round each price pi to Roundi(pi) so that the rounded array [Round1(p1),Round2(p2)...,Roundn(pn)] sums to the given target. Each operation Roundi(pi) could be either Floor(pi) or Ceil(pi).

Return the string "-1" if the rounded array is impossible to sum to target. Otherwise, return the smallest rounding error, which is defined as Σ |Roundi(pi) - (pi)| for i from 1 to n, as a string with three places after the decimal.

Example 1:

**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 .

Example 2:

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

Example 3:

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

Constraints:

• 1 <= prices.length <= 500

• Each string prices[i] represents a real number in the range [0.0, 1000.0] and has exactly 3 decimal places.

• 0 <= target <= 106

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