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Author: NamVr

1529-max-difference-you-can-get-from-changing-an-integer/README.md

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+<p>You are given an integer <code>num</code>. You will apply the following steps to <code>num</code> <strong>two</strong> separate 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>. Note <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>
+</ul>
+
+<p>Let <code>a</code> and <code>b</code> be the two results from applying the operation to <code>num</code> <em>independently</em>.</p>
+
+<p>Return <em>the max difference</em> between <code>a</code> and <code>b</code>.</p>
+
+<p>Note that neither <code>a</code> nor <code>b</code> may have any leading zeros, and <strong>must not</strong> be 0.</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>

1529-max-difference-you-can-get-from-changing-an-integer/solution.py

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+class Solution:
+    def maxDiff(self, num: int) -> int:
+
+        def swap(x,y):
+            return str(num).replace(str(x), str(y)) # change all x to y in num.
+       
+        mi = ma = num
+
+        for x in range(10):
+            for y in range(10):
+                res = swap(x,y) # this is a string!
+
+                # leading zeros check
+                if res[0] != "0":
+                    mi = min(mi, int(res))
+                    ma = max(ma, int(res))
+                
+        return ma - mi