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2819. Minimum Relative Loss After Buying Chocolates

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You are given an integer array prices, which shows the chocolate prices and a 2D integer array queries, where queries[i] = [ki, mi].

Alice and Bob went to buy some chocolates, and Alice suggested a way to pay for them, and Bob agreed.

The terms for each query are as follows:

  • If the price of a chocolate is less than or equal to ki, Bob pays for it.
  • Otherwise, Bob pays ki of it, and Alice pays the rest.

Bob wants to select exactly mi chocolates such that his relative loss is minimized, more formally, if, in total, Alice has paid ai and Bob has paid bi, Bob wants to minimize bi - ai.

Return an integer array ans where ans[i] is Bob's minimum relative loss possible for queries[i].

Example 1:

Input: prices = [1,9,22,10,19], queries = [[18,4],[5,2]]
Output: [34,-21]
Explanation: For the 1st query Bob selects the chocolates with prices [1,9,10,22]. He pays 1 + 9 + 10 + 18 = 38 and Alice pays 0 + 0 + 0 + 4 = 4. So Bob's relative loss is 38 - 4 = 34.
For the 2nd query Bob selects the chocolates with prices [19,22]. He pays 5 + 5 = 10 and Alice pays 14 + 17 = 31. So Bob's relative loss is 10 - 31 = -21.
It can be shown that these are the minimum possible relative losses.

Example 2:

Input: prices = [1,5,4,3,7,11,9], queries = [[5,4],[5,7],[7,3],[4,5]]
Output: [4,16,7,1]
Explanation: For the 1st query Bob selects the chocolates with prices [1,3,9,11]. He pays 1 + 3 + 5 + 5 = 14 and Alice pays 0 + 0 + 4 + 6 = 10. So Bob's relative loss is 14 - 10 = 4.
For the 2nd query Bob has to select all the chocolates. He pays 1 + 5 + 4 + 3 + 5 + 5 + 5 = 28 and Alice pays 0 + 0 + 0 + 0 + 2 + 6 + 4 = 12. So Bob's relative loss is 28 - 12 = 16.
For the 3rd query Bob selects the chocolates with prices [1,3,11] and he pays 1 + 3 + 7 = 11 and Alice pays 0 + 0 + 4 = 4. So Bob's relative loss is 11 - 4 = 7.
For the 4th query Bob selects the chocolates with prices [1,3,7,9,11] and he pays 1 + 3 + 4 + 4 + 4 = 16 and Alice pays 0 + 0 + 3 + 5 + 7 = 15. So Bob's relative loss is 16 - 15 = 1.
It can be shown that these are the minimum possible relative losses.

Example 3:

Input: prices = [5,6,7], queries = [[10,1],[5,3],[3,3]]
Output: [5,12,0]
Explanation: For the 1st query Bob selects the chocolate with price 5 and he pays 5 and Alice pays 0. So Bob's relative loss is 5 - 0 = 5.
For the 2nd query Bob has to select all the chocolates. He pays 5 + 5 + 5 = 15 and Alice pays 0 + 1 + 2 = 3. So Bob's relative loss is 15 - 3 = 12.
For the 3rd query Bob has to select all the chocolates. He pays 3 + 3 + 3 = 9 and Alice pays 2 + 3 + 4 = 9. So Bob's relative loss is 9 - 9 = 0.
It can be shown that these are the minimum possible relative losses.

Constraints:

  • 1 <= prices.length == n <= 105
  • 1 <= prices[i] <= 109
  • 1 <= queries.length <= 105
  • queries[i].length == 2
  • 1 <= ki <= 109
  • 1 <= mi <= n

Hints open one at a time

Hint 1
First sort prices.
Hint 2
For one query, imagine mi is 1. It can be shown that Bob should select either the first one (the cheapest one) or the last one (the most expensive).
Hint 3
Now if mi > 1, separate the chocolates into two parts. The first part is chocolates having a price less than or equal to k, the rest would be in the second part.
Hint 4
Knowing how many chocolates Bob should pick from the first part is sufficient. Of course, Bob should select a prefix from this part and a suffix from the second part.
Hint 5
To find the number of chocolates from the first part, do a binary search on the first part.
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Starter codePython 3Spaces: 4
Examples
Input
[1,9,22,10,19]
[[18,4],[5,2]]
Input
[1,5,4,3,7,11,9]
[[5,4],[5,7],[7,3],[4,5]]
Input
[5,6,7]
[[10,1],[5,3],[3,3]]
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