<p>You are given an integer <code>num</code>. You will apply the following steps exactly <strong>two</strong> times:</p>

<ul>
	<li>Pick a digit <code>x (0 &lt;= x &lt;= 9)</code>.</li>
	<li>Pick another digit <code>y (0 &lt;= y &lt;= 9)</code>. The digit <code>y</code> can be equal to <code>x</code>.</li>
	<li>Replace all the occurrences of <code>x</code> in the decimal representation of <code>num</code> by <code>y</code>.</li>
	<li>The new integer <strong>cannot</strong> have any leading zeros, also the new integer <strong>cannot</strong> be 0.</li>
</ul>

<p>Let <code>a</code> and <code>b</code> be the results of applying the operations to <code>num</code> the first and second times, respectively.</p>

<p>Return <em>the max difference</em> between <code>a</code> and <code>b</code>.</p>

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

<pre>
<strong>Input:</strong> num = 555
<strong>Output:</strong> 888
<strong>Explanation:</strong> The first time pick x = 5 and y = 9 and store the new integer in a.
The second time pick x = 5 and y = 1 and store the new integer in b.
We have now a = 999 and b = 111 and max difference = 888
</pre>

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

<pre>
<strong>Input:</strong> num = 9
<strong>Output:</strong> 8
<strong>Explanation:</strong> The first time pick x = 9 and y = 9 and store the new integer in a.
The second time pick x = 9 and y = 1 and store the new integer in b.
We have now a = 9 and b = 1 and max difference = 8
</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 {
public:
    int maxDiff(int num) {
        int small = INT_MAX;
        int big = 0;
        
        string numStr = to_string(num);
        
        for (int i = 0; i <= 9; i++) {
            for (int j = 0; j <= 9; j++) {
                string k = numStr;
                
                // Replace occurrences of digit 'i' with 'j'
                for (char &c : k) {
                    if (c == (i + '0')) {
                        c = (j + '0');
                    }
                }
                
                // Ensure no leading zeros and result is non-zero
                if (k[0] == '0') continue;
                int l = stoi(k);
                if (l == 0) continue;
                
                // Update small and big values
                small = min(l, small);
                big = max(l, big);
            }
        }
        
        return big - small;
    }
};
9700