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40 lines
1.9 KiB
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40 lines
1.9 KiB
HTML
<p>Given the strings <code>s1</code> and <code>s2</code> of size <code>n</code> and the string <code>evil</code>, return <em>the number of <strong>good</strong> strings</em>.</p>
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<p>A <strong>good</strong> string has size <code>n</code>, it is alphabetically greater than or equal to <code>s1</code>, it is alphabetically smaller than or equal to <code>s2</code>, and it does not contain the string <code>evil</code> as a substring. Since the answer can be a huge number, return this <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</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> n = 2, s1 = "aa", s2 = "da", evil = "b"
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<strong>Output:</strong> 51
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<strong>Explanation:</strong> There are 25 good strings starting with 'a': "aa","ac","ad",...,"az". Then there are 25 good strings starting with 'c': "ca","cc","cd",...,"cz" and finally there is one good string starting with 'd': "da".
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</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> n = 8, s1 = "leetcode", s2 = "leetgoes", evil = "leet"
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<strong>Output:</strong> 0
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<strong>Explanation:</strong> All strings greater than or equal to s1 and smaller than or equal to s2 start with the prefix "leet", therefore, there is not any good string.
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</pre>
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<p><strong>Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> n = 2, s1 = "gx", s2 = "gz", evil = "x"
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<strong>Output:</strong> 2
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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>s1.length == n</code></li>
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<li><code>s2.length == n</code></li>
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<li><code>s1 <= s2</code></li>
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<li><code>1 <= n <= 500</code></li>
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<li><code>1 <= evil.length <= 50</code></li>
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<li>All strings consist of lowercase English letters.</li>
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</ul>
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