1561. Maximum Number of Coins You Can Get

https://leetcode.com/problems/maximum-number-of-coins-you-can-get

Description

There are 3n piles of coins of varying size, you and your friends will take piles of coins as follows:

• In each step, you will choose any3 piles of coins (not necessarily consecutive).

• Of your choice, Alice will pick the pile with the maximum number of coins.

• You will pick the next pile with maximum number of coins.

• Your friend Bob will pick the last pile.

• Repeat until there are no more piles of coins.

Given an array of integers piles where piles[i] is the number of coins in the ith pile.

Return the maximum number of coins which you can have.

Example 1:

**Input:** piles = [2,4,1,2,7,8]
**Output:** 9
**Explanation:** Choose the triplet (2, 7, 8), Alice Pick the pile with 8 coins, you the pile with **7** coins and Bob the last one.
Choose the triplet (1, 2, 4), Alice Pick the pile with 4 coins, you the pile with **2** coins and Bob the last one.
The maximum number of coins which you can have are: 7 + 2 = 9.
On the other hand if we choose this arrangement (1, **2**, 8), (2, **4**, 7) you only get 2 + 4 = 6 coins which is not optimal.

Example 2:

**Input:** piles = [2,4,5]
**Output:** 4

Example 3:

**Input:** piles = [9,8,7,6,5,1,2,3,4]
**Output:** 18

Constraints:

• 3 <= piles.length <= 10^5

• piles.length % 3 == 0

• 1 <= piles[i] <= 10^4

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