<p>You are given an integer <code>num</code>. You know that Bob will sneakily <strong>remap</strong> one of the <code>10</code> possible digits (<code>0</code> to <code>9</code>) to another digit.</p>

<p>Return <em>the difference between the maximum and minimum&nbsp;values Bob can make by remapping&nbsp;<strong>exactly</strong> <strong>one</strong> digit in </em><code>num</code>.</p>

<p><strong>Notes:</strong></p>

<ul>
	<li>When Bob remaps a digit <font face="monospace">d1</font>&nbsp;to another digit <font face="monospace">d2</font>, Bob replaces all occurrences of <code>d1</code>&nbsp;in <code>num</code>&nbsp;with <code>d2</code>.</li>
	<li>Bob can remap a digit to itself, in which case <code>num</code>&nbsp;does not change.</li>
	<li>Bob can remap different digits for obtaining minimum and maximum values respectively.</li>
	<li>The resulting number after remapping can contain leading zeroes.</li>
</ul>

<p>&nbsp;</p>
<p><strong>Example 1:</strong></p>

<pre>
<strong>Input:</strong> num = 11891
<strong>Output:</strong> 99009
<strong>Explanation:</strong> 
To achieve the maximum value, Bob can remap the digit 1 to the digit 9 to yield 99899.
To achieve the minimum value, Bob can remap the digit 1 to the digit 0, yielding 890.
The difference between these two numbers is 99009.
</pre>

<p><strong>Example 2:</strong></p>

<pre>
<strong>Input:</strong> num = 90
<strong>Output:</strong> 99
<strong>Explanation:</strong>
The maximum value that can be returned by the function is 99 (if 0 is replaced by 9) and the minimum value that can be returned by the function is 0 (if 9 is replaced by 0).
Thus, we return 99.</pre>

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

<ul>
	<li><code>1 &lt;= num &lt;= 10<sup>8</sup></code></li>
</ul>

class Solution:
  def minMaxDifference(self, num: int) -> int:
    s = str(num)
    to9 = s[self._firstNotNineIndex(s)]
    to0 = s[0]
    return int(s.replace(to9, '9')) - int(s.replace(to0, '0'))

  def _firstNotNineIndex(self, s: str) -> int:
    for i, c in enumerate(s):
      if c != '9':
        return i
    return 0
        
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