<p>Given an array of integers <code>nums</code> and an integer <code>k</code>. A continuous subarray is called <strong>nice</strong> if there are <code>k</code> odd numbers on it.</p>

<p>Return <em>the number of <strong>nice</strong> sub-arrays</em>.</p>

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

<pre>
<strong>Input:</strong> nums = [1,1,2,1,1], k = 3
<strong>Output:</strong> 2
<strong>Explanation:</strong> The only sub-arrays with 3 odd numbers are [1,1,2,1] and [1,2,1,1].
</pre>

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

<pre>
<strong>Input:</strong> nums = [2,4,6], k = 1
<strong>Output:</strong> 0
<strong>Explanation:</strong> There are no odd numbers in the array.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> nums = [2,2,2,1,2,2,1,2,2,2], k = 2
<strong>Output:</strong> 16
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 50000</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 10^5</code></li>
	<li><code>1 &lt;= k &lt;= nums.length</code></li>
</ul>

#pragma GCC optimize("O3")
#pragma GCC target("avx2, bmi, bmi2, lzcnt, popcnt")
static const bool __boost = [](){
    cin.tie(nullptr);
    cout.tie(nullptr);
    return ios_base::sync_with_stdio(false);
}();
class Solution {
public:
int solve(vector<int>& nums, int k)
{
    int cnt=0;
        int odd=0;
        int i=0,j=0;
        while(j<nums.size())
        {
            if(nums[j]%2==1) odd++;

            while(odd>k)
            {
                if(nums[i]%2==1) odd--;
                i++;
            }
           cnt+=j-i+1;
            j++;
        }
        return cnt;

}
    int numberOfSubarrays(vector<int>& nums, int k) {
        
       return solve(nums,k)-solve(nums,k-1);
    }
};
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