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

<p>A <strong>good array</strong> is an array where the number of different integers in that array is exactly <code>k</code>.</p>

<ul>
	<li>For example, <code>[1,2,3,1,2]</code> has <code>3</code> different integers: <code>1</code>, <code>2</code>, and <code>3</code>.</li>
</ul>

<p>A <strong>subarray</strong> is a <strong>contiguous</strong> part of an array.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,2,1,2,3], k = 2
<strong>Output:</strong> 7
<strong>Explanation:</strong> Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2]
</pre>

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

<pre>
<strong>Input:</strong> nums = [1,2,1,3,4], k = 3
<strong>Output:</strong> 3
<strong>Explanation:</strong> Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
	<li><code>1 &lt;= nums[i], k &lt;= nums.length</code></li>
</ul>

class Solution {
public:

    int subArrCount(vector<int> nums, int k)
    {
        if(k<=0)return 0;

        int l = 0;
        int r = 0;
        unordered_map<int,int> mp;
        int count = 0;
        while(r < nums.size())
        {
            mp[nums[r]]++;
            if(mp.size() > k)
            {
                while(mp.size() != k)
                {
                    mp[nums[l]]--;
                    if(mp[nums[l]] == 0)mp.erase(nums[l]);
                    l++;
                }
            }
            if(mp.size() <= k)count += r-l+1;
            r++;
        }
        return count;
    }
    int subarraysWithKDistinct(vector<int>& nums, int k) 
    {
        return subArrCount(nums, k) - subArrCount(nums, k-1);    
    }
};
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