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Author: NamVr

2456-construct-smallest-number-from-di-string/README.md

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+<p>You are given a <strong>0-indexed</strong> string <code>pattern</code> of length <code>n</code> consisting of the characters <code>&#39;I&#39;</code> meaning <strong>increasing</strong> and <code>&#39;D&#39;</code> meaning <strong>decreasing</strong>.</p>
+
+<p>A <strong>0-indexed</strong> string <code>num</code> of length <code>n + 1</code> is created using the following conditions:</p>
+
+<ul>
+	<li><code>num</code> consists of the digits <code>&#39;1&#39;</code> to <code>&#39;9&#39;</code>, where each digit is used <strong>at most</strong> once.</li>
+	<li>If <code>pattern[i] == &#39;I&#39;</code>, then <code>num[i] &lt; num[i + 1]</code>.</li>
+	<li>If <code>pattern[i] == &#39;D&#39;</code>, then <code>num[i] &gt; num[i + 1]</code>.</li>
+</ul>
+
+<p>Return <em>the lexicographically <strong>smallest</strong> possible string </em><code>num</code><em> that meets the conditions.</em></p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> pattern = &quot;IIIDIDDD&quot;
+<strong>Output:</strong> &quot;123549876&quot;
+<strong>Explanation:
+</strong>At indices 0, 1, 2, and 4 we must have that num[i] &lt; num[i+1].
+At indices 3, 5, 6, and 7 we must have that num[i] &gt; num[i+1].
+Some possible values of num are &quot;245639871&quot;, &quot;135749862&quot;, and &quot;123849765&quot;.
+It can be proven that &quot;123549876&quot; is the smallest possible num that meets the conditions.
+Note that &quot;123414321&quot; is not possible because the digit &#39;1&#39; is used more than once.</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> pattern = &quot;DDD&quot;
+<strong>Output:</strong> &quot;4321&quot;
+<strong>Explanation:</strong>
+Some possible values of num are &quot;9876&quot;, &quot;7321&quot;, and &quot;8742&quot;.
+It can be proven that &quot;4321&quot; is the smallest possible num that meets the conditions.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= pattern.length &lt;= 8</code></li>
+	<li><code>pattern</code> consists of only the letters <code>&#39;I&#39;</code> and <code>&#39;D&#39;</code>.</li>
+</ul>

2456-construct-smallest-number-from-di-string/solution.py

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+class Solution:
+    def smallestNumber(self, pattern: str) -> str:
+        result = []
+        num_stack = []
+
+        # Iterate through the pattern
+        for index in range(len(pattern) + 1):
+            # Push the next number onto the stack
+            num_stack.append(index + 1)
+
+            # If 'I' is encountered or we reach the end, pop all stack elements
+            if index == len(pattern) or pattern[index] == "I":
+                while num_stack:
+                    result.append(str(num_stack.pop()))
+
+        return "".join(result)