<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:
    vector<int> nums;
    int sub(int k){
        unordered_map<int,int> cnt;
        int ans=0,left=0;
        int countDistinct = 0;
        for (int right = 0; right<nums.size();  right++){
            if (!cnt.count(nums[right])) cnt[nums[right]]=0;
            cnt[nums[right]]++;
            if(cnt[nums[right]]==1) countDistinct++;
            while(left<=right && countDistinct>k){
                cnt[nums[left]]--;
                if (cnt[nums[left]]==0) countDistinct--;
                left++;
            }
            ans+= right-left+1;
        }
        return ans;
    }
    int subarraysWithKDistinct(vector<int>& nums,int k) {
        this->nums = nums;
        cout << sub(k) << '\n';
        cout << sub(k-1) << '\n';
        return sub(k)-sub(k-1);
    }
};
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