<p>Given two integers n and k, return <em>an array of all the integers of length </em><code>n</code><em> where the difference between every two consecutive digits is </em><code>k</code>. You may return the answer in <strong>any order</strong>.</p>

<p>Note that the integers should not have leading zeros. Integers as <code>02</code> and <code>043</code> are not allowed.</p>

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

<pre>
<strong>Input:</strong> n = 3, k = 7
<strong>Output:</strong> [181,292,707,818,929]
<strong>Explanation:</strong> Note that 070 is not a valid number, because it has leading zeroes.
</pre>

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

<pre>
<strong>Input:</strong> n = 2, k = 1
<strong>Output:</strong> [10,12,21,23,32,34,43,45,54,56,65,67,76,78,87,89,98]
</pre>

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

<ul>
	<li><code>2 &lt;= n &lt;= 9</code></li>
	<li><code>0 &lt;= k &lt;= 9</code></li>
</ul>

class Solution:
    def numsSameConsecDiff(self, n: int, k: int) -> List[int]:
        valid = [0,1,2,3,4,5,6,7,8,9]
        res = []
        
        def backtrack(curr): 
            if len(curr) == n:
                if curr[0] == "0" and len(curr) > 1 or int(curr) in res:
                    return
                res.append(int(curr))
                return

            if 0 <= int(curr[-1]) + k < 10: 
                curr += str(int(curr[-1]) + k) 
                backtrack(curr) 
                curr = curr[:-1]

            if 0 <= int(curr[-1]) - k < 10: 
                curr += str(int(curr[-1]) - k) 
                backtrack(curr) 
                curr = curr[:-1] 

        for v in valid:
            backtrack(str(v)) 

        return res
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