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Author: jimit105

3309-count-prefix-and-suffix-pairs-i/README.md

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+<p>You are given a <strong>0-indexed</strong> string array <code>words</code>.</p>
+
+<p>Let&#39;s define a <strong>boolean</strong> function <code>isPrefixAndSuffix</code> that takes two strings, <code>str1</code> and <code>str2</code>:</p>
+
+<ul>
+	<li><code>isPrefixAndSuffix(str1, str2)</code> returns <code>true</code> if <code>str1</code> is <strong>both</strong> a <span data-keyword="string-prefix">prefix</span> and a <span data-keyword="string-suffix">suffix</span> of <code>str2</code>, and <code>false</code> otherwise.</li>
+</ul>
+
+<p>For example, <code>isPrefixAndSuffix(&quot;aba&quot;, &quot;ababa&quot;)</code> is <code>true</code> because <code>&quot;aba&quot;</code> is a prefix of <code>&quot;ababa&quot;</code> and also a suffix, but <code>isPrefixAndSuffix(&quot;abc&quot;, &quot;abcd&quot;)</code> is <code>false</code>.</p>
+
+<p>Return <em>an integer denoting the <strong>number</strong> of index pairs </em><code>(i, j)</code><em> such that </em><code>i &lt; j</code><em>, and </em><code>isPrefixAndSuffix(words[i], words[j])</code><em> is </em><code>true</code><em>.</em></p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> words = [&quot;a&quot;,&quot;aba&quot;,&quot;ababa&quot;,&quot;aa&quot;]
+<strong>Output:</strong> 4
+<strong>Explanation:</strong> In this example, the counted index pairs are:
+i = 0 and j = 1 because isPrefixAndSuffix(&quot;a&quot;, &quot;aba&quot;) is true.
+i = 0 and j = 2 because isPrefixAndSuffix(&quot;a&quot;, &quot;ababa&quot;) is true.
+i = 0 and j = 3 because isPrefixAndSuffix(&quot;a&quot;, &quot;aa&quot;) is true.
+i = 1 and j = 2 because isPrefixAndSuffix(&quot;aba&quot;, &quot;ababa&quot;) is true.
+Therefore, the answer is 4.</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> words = [&quot;pa&quot;,&quot;papa&quot;,&quot;ma&quot;,&quot;mama&quot;]
+<strong>Output:</strong> 2
+<strong>Explanation:</strong> In this example, the counted index pairs are:
+i = 0 and j = 1 because isPrefixAndSuffix(&quot;pa&quot;, &quot;papa&quot;) is true.
+i = 2 and j = 3 because isPrefixAndSuffix(&quot;ma&quot;, &quot;mama&quot;) is true.
+Therefore, the answer is 2.  </pre>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> words = [&quot;abab&quot;,&quot;ab&quot;]
+<strong>Output:</strong> 0
+<strong>Explanation: </strong>In this example, the only valid index pair is i = 0 and j = 1, and isPrefixAndSuffix(&quot;abab&quot;, &quot;ab&quot;) is false.
+Therefore, the answer is 0.</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= words.length &lt;= 50</code></li>
+	<li><code>1 &lt;= words[i].length &lt;= 10</code></li>
+	<li><code>words[i]</code> consists only of lowercase English letters.</li>
+</ul>

3309-count-prefix-and-suffix-pairs-i/solution.py

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+# Approach 1: Brute Force
+
+# n = number of words in input array, m = average length of words
+# Time: O(n^2 * m)
+# Space: O(1)
+
+class Solution:
+    def countPrefixSuffixPairs(self, words: List[str]) -> int:
+        n = len(words)
+        count = 0
+
+        for i in range(n):
+            for j in range(i + 1, n):
+                str1 = words[i]
+                str2 = words[j]
+
+                if len(str1) > len(str2):
+                    continue
+
+                if str2.startswith(str1) and str2.endswith(str1):
+                    count += 1
+
+        return count
+