2218 - Maximum Value of K Coins From Piles\.

Hard

There are n piles of coins on a table. Each pile consists of a positive number of coins of assorted denominations.

In one move, you can choose any coin on top of any pile, remove it, and add it to your wallet.

Given a list piles, where piles[i] is a list of integers denoting the composition of the <code>i^th</code> pile from top to bottom , and a positive integer k, return the maximum total value of coins you can have in your wallet if you choose exactly k coins optimally.

Example 1:

Input: piles = \[\[1,100,3],7,8,9], k = 2

Output: 101

Explanation: The above diagram shows the different ways we can choose k coins.

The maximum total we can obtain is 101.

Example 2:

Input: piles = \[\[100],100,100,100,100,100,1,1,1,1,1,1,700], k = 7

Output: 706

Explanation: The maximum total can be obtained if we choose all coins from the last pile.

Constraints:

• n == piles.length

• 1 <= n <= 1000

• <code>1 <= pilesj<= 10⁵</code>

• 1 <= k <= sum(piles[i].length) <= 2000