count-the-number-of-good-subarrays

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Algorithms

Given an integer array <code>nums</code> and an integer <code>k</code>, return the number of good subarrays of <code>nums</code>.

A subarray <code>arr</code> is good if there are at least <code>k</code> pairs of indices <code>(i, j)</code> such that <code>i &lt; j</code> and <code>arr[i] == arr[j]</code>.

A subarray is a contiguous non-empty sequence of elements within an array.

&nbsp;
Example 1:

<pre>
Input: nums = [1,1,1,1,1], k = 10
Output: 1
Explanation: The only good subarray is the array nums itself.
</pre>

Example 2:

<pre>
Input: nums = [3,1,4,3,2,2,4], k = 2
Output: 4
Explanation: There are 4 different good subarrays:
- [3,1,4,3,2,2] that has 2 pairs.
- [3,1,4,3,2,2,4] that has 3 pairs.
- [1,4,3,2,2,4] that has 2 pairs.
- [4,3,2,2,4] that has 2 pairs.
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= nums.length &lt;= 105</code></li>
	<li><code>1 &lt;= nums[i], k &lt;= 109</code></li>
</ul>

countGood

Count the Number of Good Subarrays

Count Number of Homogenous Substrings

count-number-of-homogenous-substrings

统计同质子字符串的数目

Maximum Sum of Distinct Subarrays With Length K

maximum-sum-of-distinct-subarrays-with-length-k

长度为 K 子数组中的最大和

Array

Hash Table

Sliding Window

给你一个整数数组 <code>nums</code>&nbsp;和一个整数 <code>k</code>&nbsp;，请你返回 <code>nums</code>&nbsp;中 好&nbsp;子数组的数目。

一个子数组 <code>arr</code>&nbsp;如果有 至少&nbsp;<code>k</code>&nbsp;对下标 <code>(i, j)</code>&nbsp;满足 <code>i &lt; j</code>&nbsp;且 <code>arr[i] == arr[j]</code>&nbsp;，那么称它是一个 好&nbsp;子数组。

子数组&nbsp;是原数组中一段连续 非空&nbsp;的元素序列。

&nbsp;

示例 1：

<pre>输入：nums = [1,1,1,1,1], k = 10
输出：1
解释：唯一的好子数组是这个数组本身。
</pre>

示例 2：

<pre>输入：nums = [3,1,4,3,2,2,4], k = 2
输出：4
解释：总共有 4 个不同的好子数组：
- [3,1,4,3,2,2] 有 2 对。
- [3,1,4,3,2,2,4] 有 3 对。
- [1,4,3,2,2,4] 有 2 对。
- [4,3,2,2,4] 有 2 对。
</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= nums.length &lt;= 105</code></li>
	<li><code>1 &lt;= nums[i], k &lt;= 109</code></li>
</ul>