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leetcode/problem/number-of-wonderful-substrings.html

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+<p>A <strong>wonderful</strong> string is a string where <strong>at most one</strong> letter appears an <strong>odd</strong> number of times.</p>
+
+
+
+<ul>
+
+	<li>For example, <code>&quot;ccjjc&quot;</code> and <code>&quot;abab&quot;</code> are wonderful, but <code>&quot;ab&quot;</code> is not.</li>
+
+</ul>
+
+
+
+<p>Given a string <code>word</code> that consists of the first ten lowercase English letters (<code>&#39;a&#39;</code> through <code>&#39;j&#39;</code>), return <em>the <strong>number of wonderful non-empty substrings</strong> in </em><code>word</code><em>. If the same substring appears multiple times in </em><code>word</code><em>, then count <strong>each occurrence</strong> separately.</em></p>
+
+
+
+<p>A <strong>substring</strong> is a contiguous sequence of characters in a string.</p>
+
+
+
+<p>&nbsp;</p>
+
+<p><strong>Example 1:</strong></p>
+
+
+
+<pre>
+
+<strong>Input:</strong> word = &quot;aba&quot;
+
+<strong>Output:</strong> 4
+
+<strong>Explanation:</strong> The four wonderful substrings are underlined below:
+
+- &quot;<u><strong>a</strong></u>ba&quot; -&gt; &quot;a&quot;
+
+- &quot;a<u><strong>b</strong></u>a&quot; -&gt; &quot;b&quot;
+
+- &quot;ab<u><strong>a</strong></u>&quot; -&gt; &quot;a&quot;
+
+- &quot;<u><strong>aba</strong></u>&quot; -&gt; &quot;aba&quot;
+
+</pre>
+
+
+
+<p><strong>Example 2:</strong></p>
+
+
+
+<pre>
+
+<strong>Input:</strong> word = &quot;aabb&quot;
+
+<strong>Output:</strong> 9
+
+<strong>Explanation:</strong> The nine wonderful substrings are underlined below: