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52 lines
2.9 KiB
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52 lines
2.9 KiB
HTML
<p>Every <strong>valid email</strong> consists of a <strong>local name</strong> and a <strong>domain name</strong>, separated by the <code>'@'</code> sign. Besides lowercase letters, the email may contain one or more <code>'.'</code> or <code>'+'</code>.</p>
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<ul>
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<li>For example, in <code>"alice@leetcode.com"</code>, <code>"alice"</code> is the <strong>local name</strong>, and <code>"leetcode.com"</code> is the <strong>domain name</strong>.</li>
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</ul>
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<p>If you add periods <code>'.'</code> between some characters in the <strong>local name</strong> part of an email address, mail sent there will be forwarded to the same address without dots in the local name. Note that this rule <strong>does not apply</strong> to <strong>domain names</strong>.</p>
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<ul>
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<li>For example, <code>"alice.z@leetcode.com"</code> and <code>"alicez@leetcode.com"</code> forward to the same email address.</li>
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</ul>
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<p>If you add a plus <code>'+'</code> in the <strong>local name</strong>, everything after the first plus sign <strong>will be ignored</strong>. This allows certain emails to be filtered. Note that this rule <strong>does not apply</strong> to <strong>domain names</strong>.</p>
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<ul>
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<li>For example, <code>"m.y+name@email.com"</code> will be forwarded to <code>"my@email.com"</code>.</li>
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</ul>
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<p>It is possible to use both of these rules at the same time.</p>
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<p>Given an array of strings <code>emails</code> where we send one email to each <code>emails[i]</code>, return <em>the number of different addresses that actually receive mails</em>.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> emails = ["test.email+alex@leetcode.com","test.e.mail+bob.cathy@leetcode.com","testemail+david@lee.tcode.com"]
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<strong>Output:</strong> 2
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<strong>Explanation:</strong> "testemail@leetcode.com" and "testemail@lee.tcode.com" actually receive mails.
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> emails = ["a@leetcode.com","b@leetcode.com","c@leetcode.com"]
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<strong>Output:</strong> 3
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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 <= emails.length <= 100</code></li>
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<li><code>1 <= emails[i].length <= 100</code></li>
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<li><code>emails[i]</code> consist of lowercase English letters, <code>'+'</code>, <code>'.'</code> and <code>'@'</code>.</li>
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<li>Each <code>emails[i]</code> contains exactly one <code>'@'</code> character.</li>
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<li>All local and domain names are non-empty.</li>
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<li>Local names do not start with a <code>'+'</code> character.</li>
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<li>Domain names end with the <code>".com"</code> suffix.</li>
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<li>Domain names must contain at least one character before <code>".com"</code> suffix.</li>
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</ul>
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