2218.Maximum Value of K Coins From Piles === ###### tags: `Hard`,`Array`,`DP`,`Prefix Sum` [2218. Maximum Value of K Coins From Piles](https://leetcode.com/problems/maximum-value-of-k-coins-from-piles/) ### 題目描述 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 i^th^ 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.* ### 範例 **Example 1:** ![](https://assets.leetcode.com/uploads/2019/11/09/e1.png =80%x) ``` 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]` <= 10^5^ * 1 <= `k` <= `sum(piles[i].length)` <= 2000 ### 解答 ### Reference [回到題目列表](https://hackmd.io/@Marsgoat/leetcode_every_day)