update

leetcode/problem/count-number-of-homogenous-substrings.html

@@ -0,0 +1,43 @@
+<p>Given a string <code>s</code>, return <em>the number of <strong>homogenous</strong> substrings of </em><code>s</code><em>.</em> Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
+
+
+
+<p>A string is <strong>homogenous</strong> if all the characters of the string are the same.</p>
+
+
+
+<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
+
+
+
+<p>&nbsp;</p>
+
+<p><strong>Example 1:</strong></p>
+
+
+
+<pre>
+
+<strong>Input:</strong> s = &quot;abbcccaa&quot;
+
+<strong>Output:</strong> 13
+
+<strong>Explanation:</strong> The homogenous substrings are listed as below:
+
+&quot;a&quot;   appears 3 times.
+
+&quot;aa&quot;  appears 1 time.
+
+&quot;b&quot;   appears 2 times.
+
+&quot;bb&quot;  appears 1 time.
+
+&quot;c&quot;   appears 3 times.
+
+&quot;cc&quot;  appears 2 times.
+
+&quot;ccc&quot; appears 1 time.
+
+3 + 1 + 2 + 1 + 3 + 2 + 1 = 13.</pre>
+
+