<p>You wrote down many <strong>positive</strong> integers in a string called <code>num</code>. However, you realized that you forgot to add commas to seperate the different numbers. You remember that the list of integers was <strong>non-decreasing</strong> and that <strong>no</strong> integer had leading zeros.</p>

<p>Return <em>the <strong>number of possible lists of integers</strong> that you could have written down to get the string </em><code>num</code>. Since the answer may be 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>

<pre>
<strong>Input:</strong> num = &quot;327&quot;
<strong>Output:</strong> 2
<strong>Explanation:</strong> You could have written down the numbers:
3, 27
327
</pre>

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

<pre>
<strong>Input:</strong> num = &quot;094&quot;
<strong>Output:</strong> 0
<strong>Explanation:</strong> No numbers can have leading zeros and all numbers must be positive.
</pre>

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

<pre>
<strong>Input:</strong> num = &quot;0&quot;
<strong>Output:</strong> 0
<strong>Explanation:</strong> No numbers can have leading zeros and all numbers must be positive.
</pre>

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

<ul>
	<li><code>1 &lt;= num.length &lt;= 3500</code></li>
	<li><code>num</code> consists of digits <code>&#39;0&#39;</code> through <code>&#39;9&#39;</code>.</li>
</ul>

class Solution:
    def numberOfCombinations(self, num: str) -> int:
        n = len(num)
        prev = [0]*n
        m = 1000000007
        for L in range(1,n+1):
            curr = [0]*n
            pfstr = [0]*(n+1)
            idx = n-1
            while idx-L>=0:
                if num[idx]==num[idx-L]:
                    pfstr[idx] = pfstr[idx+1] + 1
                idx-=1
            for i in range(n):
                iS,iE = i-L+1,i
                jS,jE = iS-L,iS-1
                if iS<0:
                    curr[i] = prev[i]
                elif num[iS]=="0":
                    curr[i] = prev[i]
                elif iS==0:
                    curr[i] = prev[i] + 1
                elif jS<0:
                    curr[i] = curr[jE] + prev[i]
                else:
                    pf_len = min(pfstr[iS],L)
                    if (pf_len == L) or (num[iS+pf_len] > num[jS+pf_len]):
                        curr[i] = curr[jE] + prev[i]
                    else:
                        curr[i] = prev[jE] + prev[i]
            prev = curr
        ans = prev[n-1]
        return ans%m
                


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