maximum-number-of-pairs-in-array

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Algorithms

You are given a 0-indexed integer array <code>nums</code>. In one operation, you may do the following:

<ul>
	<li>Choose two integers in <code>nums</code> that are equal.</li>
	<li>Remove both integers from <code>nums</code>, forming a pair.</li>
</ul>

The operation is done on <code>nums</code> as many times as possible.

Return a 0-indexed integer array <code>answer</code> of size <code>2</code> where <code>answer[0]</code> is the number of pairs that are formed and <code>answer[1]</code> is the number of leftover integers in <code>nums</code> after doing the operation as many times as possible.

&nbsp;
Example 1:

<pre>
Input: nums = [1,3,2,1,3,2,2]
Output: [3,1]
Explanation:
Form a pair with nums[0] and nums[3] and remove them from nums. Now, nums = [3,2,3,2,2].
Form a pair with nums[0] and nums[2] and remove them from nums. Now, nums = [2,2,2].
Form a pair with nums[0] and nums[1] and remove them from nums. Now, nums = [2].
No more pairs can be formed. A total of 3 pairs have been formed, and there is 1 number leftover in nums.
</pre>

Example 2:

<pre>
Input: nums = [1,1]
Output: [1,0]
Explanation: Form a pair with nums[0] and nums[1] and remove them from nums. Now, nums = [].
No more pairs can be formed. A total of 1 pair has been formed, and there are 0 numbers leftover in nums.
</pre>

Example 3:

<pre>
Input: nums = [0]
Output: [0,1]
Explanation: No pairs can be formed, and there is 1 number leftover in nums.
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
	<li><code>0 &lt;= nums[i] &lt;= 100</code></li>
</ul>

numberOfPairs

Maximum Number of Pairs in Array

Sort Characters By Frequency

sort-characters-by-frequency

根据字符出现频率排序

Top K Frequent Words

top-k-frequent-words

前K个高频单词

Sort Array by Increasing Frequency

sort-array-by-increasing-frequency

按照频率将数组升序排序

Array

Hash Table

Counting

给你一个下标从 0 开始的整数数组 <code>nums</code> 。在一步操作中，你可以执行以下步骤：

<ul>
	<li>从 <code>nums</code> 选出 两个 相等的 整数</li>
	<li>从 <code>nums</code> 中移除这两个整数，形成一个 数对</li>
</ul>

请你在 <code>nums</code> 上多次执行此操作直到无法继续执行。

返回一个下标从 0 开始、长度为 <code>2</code> 的整数数组 <code>answer</code> 作为答案，其中 <code>answer[0]</code> 是形成的数对数目，<code>answer[1]</code> 是对 <code>nums</code> 尽可能执行上述操作后剩下的整数数目。

&nbsp;

示例 1：

<pre>输入：nums = [1,3,2,1,3,2,2]
输出：[3,1]
解释：
nums[0] 和 nums[3] 形成一个数对，并从 nums 中移除，nums = [3,2,3,2,2] 。
nums[0] 和 nums[2] 形成一个数对，并从 nums 中移除，nums = [2,2,2] 。
nums[0] 和 nums[1] 形成一个数对，并从 nums 中移除，nums = [2] 。
无法形成更多数对。总共形成 3 个数对，nums 中剩下 1 个数字。</pre>

示例 2：

<pre>输入：nums = [1,1]
输出：[1,0]
解释：nums[0] 和 nums[1] 形成一个数对，并从 nums 中移除，nums = [] 。
无法形成更多数对。总共形成 1 个数对，nums 中剩下 0 个数字。</pre>

示例 3：

<pre>输入：nums = [0]
输出：[0,1]
解释：无法形成数对，nums 中剩下 1 个数字。
</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
	<li><code>0 &lt;= nums[i] &lt;= 100</code></li>
</ul>