<p>Given a binary array <code>nums</code> and an integer <code>goal</code>, return <em>the number of non-empty <strong>subarrays</strong> with a sum</em> <code>goal</code>.</p>

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

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

<pre>
<strong>Input:</strong> nums = [1,0,1,0,1], goal = 2
<strong>Output:</strong> 4
<strong>Explanation:</strong> The 4 subarrays are bolded and underlined below:
[<u><strong>1,0,1</strong></u>,0,1]
[<u><strong>1,0,1,0</strong></u>,1]
[1,<u><strong>0,1,0,1</strong></u>]
[1,0,<u><strong>1,0,1</strong></u>]
</pre>

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

<pre>
<strong>Input:</strong> nums = [0,0,0,0,0], goal = 0
<strong>Output:</strong> 15
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
	<li><code>0 &lt;= goal &lt;= nums.length</code></li>
</ul>

class Solution:
    def numSubarraysWithSum(self, nums: List[int], goal: int) -> int:

        def coun(n):
            s=0
            for i in range(1,n+1):
                s+=i
            return s

        if goal==0:
            c=0
            f=0
            flag=False
            if 0 not in nums:
                return 0
            for i in nums:
                if i==0:
                    c+=1
                else:
                    flag=True
                    f+=coun(c)
                    c=0
            if flag==False:
                return coun(len(nums))
            if c!=0:
                return f+coun(c)
                
        
        
        q=[-1]
        for i in range(len(nums)):
            if nums[i]:
                q.append(i)
        q.append(len(nums))

        i=0
        j=goal
        s=0
        while(j<len(q)-1):
            s+=(q[i+1]-q[i]-1)+(q[j+1]-q[j]-1)+1+((q[i+1]-q[i]-1)*(q[j+1]-q[j]-1))
            i+=1
            j+=1
            #print(s)
        return s
            


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