beautiful-arrangement-ii

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Algorithms

Given two integers <code>n</code> and <code>k</code>, construct a list <code>answer</code> that contains <code>n</code> different positive integers ranging from <code>1</code> to <code>n</code> and obeys the following requirement:

<ul>
	<li>Suppose this list is <code>answer =&nbsp;[a1, a2, a3, ... , an]</code>, then the list <code>[|a1 - a2|, |a2 - a3|, |a3 - a4|, ... , |an-1 - an|]</code> has exactly <code>k</code> distinct integers.</li>
</ul>

Return the list <code>answer</code>. If there multiple valid answers, return any of them.

&nbsp;
Example 1:

<pre>
Input: n = 3, k = 1
Output: [1,2,3]
Explanation: The [1,2,3] has three different positive integers ranging from 1 to 3, and the [1,1] has exactly 1 distinct integer: 1
</pre>

Example 2:

<pre>
Input: n = 3, k = 2
Output: [1,3,2]
Explanation: The [1,3,2] has three different positive integers ranging from 1 to 3, and the [2,1] has exactly 2 distinct integers: 1 and 2.
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= k &lt; n &lt;= 104</code></li>
</ul>

constructArray

Beautiful Arrangement II

Beautiful Arrangement

beautiful-arrangement

优美的排列

Array

Math

给你两个整数 <code>n</code> 和 <code>k</code> ，请你构造一个答案列表 <code>answer</code> ，该列表应当包含从 <code>1</code> 到 <code>n</code> 的 <code>n</code> 个不同正整数，并同时满足下述条件：

<ul>
	<li>假设该列表是 <code>answer = [a1, a2, a3, ... , an]</code> ，那么列表 <code>[|a1 - a2|, |a2 - a3|, |a3 - a4|, ... , |an-1 - an|]</code> 中应该有且仅有 <code>k</code> 个不同整数。</li>
</ul>

返回列表 <code>answer</code> 。如果存在多种答案，只需返回其中 任意一种 。

 

示例 1：

<pre>
输入：n = 3, k = 1
输出：[1, 2, 3]
解释：[1, 2, 3] 包含 3 个范围在 1-3 的不同整数，并且 [1, 1] 中有且仅有 1 个不同整数：1
</pre>

示例 2：

<pre>
输入：n = 3, k = 2
输出：[1, 3, 2]
解释：[1, 3, 2] 包含 3 个范围在 1-3 的不同整数，并且 [2, 1] 中有且仅有 2 个不同整数：1 和 2
</pre>

 

提示：

<ul>
	<li><code>1 <= k < n <= 104</code></li>
</ul>