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41 lines
1.9 KiB
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41 lines
1.9 KiB
HTML
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<p>给你两个长度为 <code>n</code> 的字符串 <code>s1</code> 和 <code>s2</code> ，以及一个字符串 <code>evil</code> 。请你返回 <strong>好字符串 </strong>的数目。</p>
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<p><strong>好字符串</strong> 的定义为：它的长度为 <code>n</code> ，字典序大于等于 <code>s1</code> ，字典序小于等于 <code>s2</code> ，且不包含 <code>evil</code> 为子字符串。</p>
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<p>由于答案可能很大，请你返回答案对 10^9 + 7 取余的结果。</p>
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<p> </p>
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<p><strong>示例 1：</strong></p>
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<pre><strong>输入：</strong>n = 2, s1 = "aa", s2 = "da", evil = "b"
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<strong>输出：</strong>51
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<strong>解释：</strong>总共有 25 个以 'a' 开头的好字符串："aa"，"ac"，"ad"，...，"az"。还有 25 个以 'c' 开头的好字符串："ca"，"cc"，"cd"，...，"cz"。最后，还有一个以 'd' 开头的好字符串："da"。
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</pre>
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<p><strong>示例 2：</strong></p>
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<pre><strong>输入：</strong>n = 8, s1 = "leetcode", s2 = "leetgoes", evil = "leet"
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<strong>输出：</strong>0
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<strong>解释：</strong>所有字典序大于等于 s1 且小于等于 s2 的字符串都以 evil 字符串 "leet" 开头。所以没有好字符串。
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</pre>
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<p><strong>示例 3：</strong></p>
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<pre><strong>输入：</strong>n = 2, s1 = "gx", s2 = "gz", evil = "x"
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<strong>输出：</strong>2
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</pre>
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<p> </p>
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<p><strong>提示：</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>所有字符串都只包含小写英文字母。</li>
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</ul>
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