2218. Maximum Value of K Coins From Piles

Problem Link

Description

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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 ith 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
• 1 <= piles[i][j] <= 105
• 1 <= k <= sum(piles[i].length) <= 2000

Solution

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Python3

class Solution:
    def maxValueOfCoins(self, piles: List[List[int]], K: int) -> int:
        rows, cols = len(piles), len(piles[0])
        
        @cache
        def go(index, rem):
            if rem == 0 or index == rows: return 0
 
            res = go(index + 1, rem)
            curr = 0
 
            for x in piles[index]:
                curr += x
                rem -= 1
 
                res = max(res, curr + go(index + 1, rem))
 
                if rem <= 0: break
            
            return res
        
        return go(0, K)