<p>You are given an array <code>nums</code> consisting of positive integers.</p>

<p>We call two integers <code>x</code> and <code>y</code> in this problem <strong>almost equal</strong> if both integers can become equal after performing the following operation <strong>at most once</strong>:</p>

<ul>
	<li>Choose <strong>either</strong> <code>x</code> or <code>y</code> and swap any two digits within the chosen number.</li>
</ul>

<p>Return the number of indices <code>i</code> and <code>j</code> in <code>nums</code> where <code>i &lt; j</code> such that <code>nums[i]</code> and <code>nums[j]</code> are <strong>almost equal</strong>.</p>

<p><strong>Note</strong> that it is allowed for an integer to have leading zeros after performing an operation.</p>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">nums = [3,12,30,17,21]</span></p>

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

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

<p>The almost equal pairs of elements are:</p>

<ul>
	<li>3 and 30. By swapping 3 and 0 in 30, you get 3.</li>
	<li>12 and 21. By swapping 1 and 2 in 12, you get 21.</li>
</ul>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">nums = [1,1,1,1,1]</span></p>

<p><strong>Output:</strong> <span class="example-io">10</span></p>

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

<p>Every two elements in the array are almost equal.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">nums = [123,231]</span></p>

<p><strong>Output:</strong> <span class="example-io">0</span></p>

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

<p>We cannot swap any two digits of 123 or 231 to reach the other.</p>
</div>

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

<ul>
	<li><code>2 &lt;= nums.length &lt;= 100</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
</ul>

class Solution:
    def countPairs(self, nums: List[int]) -> int:
        counter = Counter(nums) 
        identicals = sum(v * (v - 1) // 2 for v in counter.values())
        keys = list(counter.keys())
        count = 0
        for i in range(len(keys) - 1):
            for j in range(i+1, len(keys)):
                si, sj = str(keys[i]), str(keys[j])
                li, lj = len(si), len(sj)
                si = (lj - li) * '0' + si  if lj > li else si     
                sj = (li - lj) * '0' + sj  if li > lj else sj
                if Counter(si) == Counter(sj) and sum(c1 != c2 for c1, c2 in zip(si, sj)) == 2:
                    count += (counter[keys[i]] * counter[keys[j]])
        return count + identicals
16300