leetcode-problemset/leetcode-cn/problem (Chinese)/交替组 II [alternating-groups-ii].html

<p>给你一个整数数组 <code>colors</code>&nbsp;和一个整数&nbsp;<code>k</code>&nbsp;，<code>colors</code>表示一个由红色和蓝色瓷砖组成的环，第 <code>i</code>&nbsp;块瓷砖的颜色为&nbsp;<code>colors[i]</code>&nbsp;：</p>

<ul>
	<li><code>colors[i] == 0</code>&nbsp;表示第&nbsp;<code>i</code>&nbsp;块瓷砖的颜色是 <strong>红色</strong>&nbsp;。</li>
	<li><code>colors[i] == 1</code>&nbsp;表示第 <code>i</code>&nbsp;块瓷砖的颜色是 <strong>蓝色</strong>&nbsp;。</li>
</ul>

<p>环中连续 <code>k</code>&nbsp;块瓷砖的颜色如果是 <strong>交替</strong>&nbsp;颜色（也就是说除了第一块和最后一块瓷砖以外，中间瓷砖的颜色与它<strong>&nbsp;左边</strong>&nbsp;和 <strong>右边</strong>&nbsp;的颜色都不同），那么它被称为一个 <strong>交替</strong>&nbsp;组。</p>

<p>请你返回 <strong>交替</strong>&nbsp;组的数目。</p>

<p><b>注意</b>&nbsp;，由于&nbsp;<code>colors</code>&nbsp;表示一个 <strong>环</strong>&nbsp;，<strong>第一块</strong>&nbsp;瓷砖和 <strong>最后一块</strong>&nbsp;瓷砖是相邻的。</p>

<p>&nbsp;</p>

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

<div class="example-block">
<p><span class="example-io"><b>输入：</b>colors = [0,1,0,1,0], k = 3</span></p>

<p><span class="example-io"><b>输出：</b>3</span></p>

<p><strong>解释：</strong></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2024/06/19/screenshot-2024-05-28-183519.png" style="width: 150px; height: 150px; padding: 10px; background: #fff; border-radius: .5rem;" /></p>

<p>交替组包括：</p>

<p><strong class="example"><img alt="" src="https://assets.leetcode.com/uploads/2024/05/28/screenshot-2024-05-28-182448.png" style="width: 150px; height: 150px; padding: 10px; background: #fff; border-radius: .5rem;" /></strong><img alt="" src="https://assets.leetcode.com/uploads/2024/05/28/screenshot-2024-05-28-182844.png" style="width: 150px; height: 150px; padding: 10px; background: #fff; border-radius: .5rem;" /><strong class="example"><img alt="" src="https://assets.leetcode.com/uploads/2024/05/28/screenshot-2024-05-28-183057.png" style="width: 150px; height: 150px; padding: 10px; background: #fff; border-radius: .5rem;" /></strong></p>
</div>

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

<div class="example-block">
<p><span class="example-io"><b>输入：</b>colors = [0,1,0,0,1,0,1], k = 6</span></p>

<p><b>输出：</b>2</p>

<p><b>解释：</b></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2024/06/19/screenshot-2024-05-28-183907.png" style="width: 150px; height: 150px; padding: 10px; background: #fff; border-radius: .5rem;" /></p>

<p>交替组包括：</p>

<p><strong class="example"><img alt="" src="https://assets.leetcode.com/uploads/2024/06/19/screenshot-2024-05-28-184128.png" style="width: 150px; height: 150px; padding: 10px; background: #fff; border-radius: .5rem;" /></strong><img alt="" src="https://assets.leetcode.com/uploads/2024/06/19/screenshot-2024-05-28-184240.png" style="width: 150px; height: 150px; padding: 10px; background: #fff; border-radius: .5rem;" /></p>

<p><strong>示例 3：</strong></p>

<p><strong>输入：</strong>colors = [1,1,0,1], k = 4</p>

<p><strong>输出：</strong>0</p>

<p><strong>解释：</strong></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2024/06/19/screenshot-2024-05-28-184516.png" style="width: 150px; height: 150px; padding: 10px; background: #fff; border-radius: .5rem;" /></p>
</div>

<p>&nbsp;</p>

<p><strong>提示：</strong></p>

<ul>
	<li><code>3 &lt;= colors.length &lt;= 10<sup>5</sup></code></li>
	<li><code>0 &lt;= colors[i] &lt;= 1</code></li>
	<li><code>3 &lt;= k &lt;= colors.length</code></li>
</ul>