<p>You are given 3 positive integers <code>zero</code>, <code>one</code>, and <code>limit</code>.</p>

<p>A <span data-keyword="binary-array">binary array</span> <code>arr</code> is called <strong>stable</strong> if:</p>

<ul>
	<li>The number of occurrences of 0 in <code>arr</code> is <strong>exactly </strong><code>zero</code>.</li>
	<li>The number of occurrences of 1 in <code>arr</code> is <strong>exactly</strong> <code>one</code>.</li>
	<li>Each <span data-keyword="subarray-nonempty">subarray</span> of <code>arr</code> with a size greater than <code>limit</code> must contain <strong>both </strong>0 and 1.</li>
</ul>

<p>Return the <em>total</em> number of <strong>stable</strong> binary arrays.</p>

<p>Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">zero = 1, one = 1, limit = 2</span></p>

<p><strong>Output:</strong> <span class="example-io">2</span></p>

<p><strong>Explanation:</strong></p>

<p>The two possible stable binary arrays are <code>[1,0]</code> and <code>[0,1]</code>.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">zero = 1, one = 2, limit = 1</span></p>

<p><strong>Output:</strong> <span class="example-io">1</span></p>

<p><strong>Explanation:</strong></p>

<p>The only possible stable binary array is <code>[1,0,1]</code>.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">zero = 3, one = 3, limit = 2</span></p>

<p><strong>Output:</strong> <span class="example-io">14</span></p>

<p><strong>Explanation:</strong></p>

<p>All the possible stable binary arrays are <code>[0,0,1,0,1,1]</code>, <code>[0,0,1,1,0,1]</code>, <code>[0,1,0,0,1,1]</code>, <code>[0,1,0,1,0,1]</code>, <code>[0,1,0,1,1,0]</code>, <code>[0,1,1,0,0,1]</code>, <code>[0,1,1,0,1,0]</code>, <code>[1,0,0,1,0,1]</code>, <code>[1,0,0,1,1,0]</code>, <code>[1,0,1,0,0,1]</code>, <code>[1,0,1,0,1,0]</code>, <code>[1,0,1,1,0,0]</code>, <code>[1,1,0,0,1,0]</code>, and <code>[1,1,0,1,0,0]</code>.</p>
</div>

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

<ul>
	<li><code>1 &lt;= zero, one, limit &lt;= 1000</code></li>
</ul>

P = 1_000_000_007

def f(cases, other, max_size, limit):
    b = [0]
    seq_len = len(other)-1
    for i in range(min(len(cases), max_size)):
        val = cases[i]
        j = seq_len-i
        if 0 < j < len(other[-1]):
            val += other[-1][j]
        if seq_len >= limit and j < len(other[seq_len-limit]):
            val -=  other[seq_len-limit][j]
        b.append(val % P)
    return b


class Solution:
    def numberOfStableArrays(self, zero: int, one: int, limit: int) -> int:
        
        b_zero = b_one =[1]
        a_zero = [b_zero]
        a_one = [b_one]
        
        for _ in range(zero+one):
            b_zero = f(b_zero, a_one, zero, limit)
            b_one = f(b_one, a_zero, one, limit)
            a_zero.append(b_zero)
            a_one.append(b_one)

        val = 0
        if len(b_one) > one:
            val += b_one[one]
        if len(b_zero) > zero:
            val += b_zero[zero]
        
        return val % P
105200