add leetcode problem-cn part1

算法题（国内版）/problem (English)/从栈中取出 K 个硬币的最大面值和(English) [maximum-value-of-k-coins-from-piles].html

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+<p>There are <code>n</code> <strong>piles</strong> of coins on a table. Each pile consists of a <strong>positive number</strong> of coins of assorted denominations.</p>
+
+<p>In one move, you can choose any coin on <strong>top</strong> of any pile, remove it, and add it to your wallet.</p>
+
+<p>Given a list <code>piles</code>, where <code>piles[i]</code> is a list of integers denoting the composition of the <code>i<sup>th</sup></code> pile from <strong>top to bottom</strong>, and a positive integer <code>k</code>, return <em>the <strong>maximum total value</strong> of coins you can have in your wallet if you choose <strong>exactly</strong></em> <code>k</code> <em>coins optimally</em>.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2019/11/09/e1.png" style="width: 600px; height: 243px;" />
+<pre>
+<strong>Input:</strong> piles = [[1,100,3],[7,8,9]], k = 2
+<strong>Output:</strong> 101
+<strong>Explanation:</strong>
+The above diagram shows the different ways we can choose k coins.
+The maximum total we can obtain is 101.
+</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> piles = [[100],[100],[100],[100],[100],[100],[1,1,1,1,1,1,700]], k = 7
+<strong>Output:</strong> 706
+<strong>Explanation:
+</strong>The maximum total can be obtained if we choose all coins from the last pile.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>n == piles.length</code></li>
+	<li><code>1 &lt;= n &lt;= 1000</code></li>
+	<li><code>1 &lt;= piles[i][j] &lt;= 10<sup>5</sup></code></li>
+	<li><code>1 &lt;= k &lt;= sum(piles[i].length) &lt;= 2000</code></li>
+</ul>