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43 lines
1.5 KiB
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43 lines
1.5 KiB
HTML
<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>
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<p>A string is <strong>homogenous</strong> if all the characters of the string are the same.</p>
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<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> s = "abbcccaa"
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<strong>Output:</strong> 13
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<strong>Explanation:</strong> The homogenous substrings are listed as below:
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"a" appears 3 times.
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"aa" appears 1 time.
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"b" appears 2 times.
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"bb" appears 1 time.
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"c" appears 3 times.
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"cc" appears 2 times.
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"ccc" appears 1 time.
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3 + 1 + 2 + 1 + 3 + 2 + 1 = 13.</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> s = "xy"
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<strong>Output:</strong> 2
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<strong>Explanation:</strong> The homogenous substrings are "x" and "y".</pre>
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<p><strong>Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> s = "zzzzz"
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<strong>Output:</strong> 15
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>1 <= s.length <= 10<sup>5</sup></code></li>
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<li><code>s</code> consists of lowercase letters.</li>
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</ul> |