leetcode-problemset/leetcode-cn/problem (Chinese)/三段式数组 II [trionic-array-ii].html

<p data-end="191" data-start="0">给你一个长度为 <code data-end="75" data-start="72">n</code> 的整数数组 <code data-end="61" data-start="55">nums</code>。</p>

<p data-end="191" data-start="0"><strong data-end="99" data-is-only-node="" data-start="79">三段式子数组</strong> 是一个连续子数组 <code data-end="136" data-start="125">nums[l...r]</code>（满足 <code data-end="158" data-start="143">0 &lt;= l &lt; r &lt; n</code>），并且存在下标&nbsp;<code>l &lt; p &lt; q &lt; r</code>，使得：</p>

<ul>
	<li data-end="267" data-start="230"><code data-end="241" data-start="230">nums[l...p]</code> <strong>严格</strong> 递增，</li>
	<li data-end="307" data-start="270"><code data-end="281" data-start="270">nums[p...q]</code> <strong>严格</strong> 递减，</li>
	<li data-end="347" data-start="310"><code data-end="321" data-start="310">nums[q...r]</code> <strong>严格</strong> 递增。</li>
</ul>

<p data-end="609" data-is-last-node="" data-is-only-node="" data-start="349">请你从数组 <code data-end="417" data-start="411">nums</code>&nbsp;的所有三段式子数组中找出和最大的那个，并返回其&nbsp;<strong>最大&nbsp;</strong>和。</p>

<p>&nbsp;</p>

<p><strong class="example">示例 1：</strong></p>

<div class="example-block">
<p><strong>输入：</strong><span class="example-io">nums = [0,-2,-1,-3,0,2,-1]</span></p>

<p><strong>输出：</strong><span class="example-io">-4</span></p>

<p><strong>解释：</strong></p>

<p data-end="129" data-start="72">选择 <code data-end="99" data-start="92">l = 1</code>, <code data-end="108" data-start="101">p = 2</code>, <code data-end="117" data-start="110">q = 3</code>, <code data-end="126" data-start="119">r = 5</code>：</p>

<ul>
	<li data-end="203" data-start="132"><code data-end="166" data-start="132">nums[l...p] = nums[1...2] = [-2, -1]</code> 严格递增&nbsp;(<code data-end="200" data-start="191">-2 &lt; -1</code>)。</li>
	<li data-end="277" data-start="206"><code data-end="240" data-start="206">nums[p...q] = nums[2...3] = [-1, -3]</code> 严格递减&nbsp;(<code data-end="274" data-start="265">-1 &gt; -3</code>)。</li>
	<li data-end="396" data-start="280"><code data-end="316" data-start="280">nums[q...r] = nums[3...5] = [-3, 0, 2]</code> 严格递增&nbsp;(<code data-end="353" data-start="341">-3 &lt; 0 &lt; 2</code>)。</li>
	<li data-end="396" data-start="280">和 = <code>(-2) + (-1) + (-3) + 0 + 2 = -4</code>。</li>
</ul>
</div>

<p><strong class="example">示例 2:</strong></p>

<div class="example-block">
<p><strong>输入:</strong> <span class="example-io">nums = [1,4,2,7]</span></p>

<p><strong>输出:</strong> <span class="example-io">14</span></p>

<p><strong>解释:</strong></p>

<p data-end="519" data-start="462">选择 <code data-end="489" data-start="482">l = 0</code>, <code data-end="498" data-start="491">p = 1</code>, <code data-end="507" data-start="500">q = 2</code>, <code data-end="516" data-start="509">r = 3</code>：</p>

<ul>
	<li data-end="589" data-start="522"><code data-end="554" data-start="522">nums[l...p] = nums[0...1] = [1, 4]</code> 严格递增&nbsp;(<code data-end="586" data-start="579">1 &lt; 4</code>)。</li>
	<li data-end="659" data-start="592"><code data-end="624" data-start="592">nums[p...q] = nums[1...2] = [4, 2]</code> 严格递减&nbsp;(<code data-end="656" data-start="649">4 &gt; 2</code>)。</li>
	<li data-end="754" data-is-last-node="" data-start="662"><code data-end="694" data-start="662">nums[q...r] = nums[2...3] = [2, 7]</code> 严格递增&nbsp;(<code data-end="726" data-start="719">2 &lt; 7</code>)。</li>
	<li data-end="754" data-is-last-node="" data-start="662">和 = <code>1 + 4 + 2 + 7 = 14</code>。</li>
</ul>
</div>

<p>&nbsp;</p>

<p><strong>提示:</strong></p>

<ul>
	<li data-end="883" data-start="851"><code data-end="881" data-start="851">4 &lt;= n = nums.length &lt;= 10<sup>5</sup></code></li>
	<li data-end="914" data-start="886"><code data-end="912" data-start="886">-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
	<li data-end="978" data-is-last-node="" data-start="917">保证至少存在一个三段式子数组。</li>
</ul>