Class Encrypter
java.lang.Object
g2201_2300.s2227_encrypt_and_decrypt_strings.Encrypter
2227 - Encrypt and Decrypt Strings.<p>Hard</p>
<p>You are given a character array <code>keys</code> containing <strong>unique</strong> characters and a string array <code>values</code> containing strings of length 2. You are also given another string array <code>dictionary</code> that contains all permitted original strings after decryption. You should implement a data structure that can encrypt or decrypt a <strong>0-indexed</strong> string.</p>
<p>A string is <strong>encrypted</strong> with the following process:</p>
<ol>
<li>For each character <code>c</code> in the string, we find the index <code>i</code> satisfying <code>keys[i] == c</code> in <code>keys</code>.</li>
<li>Replace <code>c</code> with <code>values[i]</code> in the string.</li>
</ol>
<p>Note that in case a character of the string is <strong>not present</strong> in <code>keys</code>, the encryption process cannot be carried out, and an empty string <code>""</code> is returned.</p>
<p>A string is <strong>decrypted</strong> with the following process:</p>
<ol>
<li>For each substring <code>s</code> of length 2 occurring at an even index in the string, we find an <code>i</code> such that <code>values[i] == s</code>. If there are multiple valid <code>i</code>, we choose <strong>any</strong> one of them. This means a string could have multiple possible strings it can decrypt to.</li>
<li>Replace <code>s</code> with <code>keys[i]</code> in the string.</li>
</ol>
<p>Implement the <code>Encrypter</code> class:</p>
<ul>
<li><code>Encrypter(char[] keys, String[] values, String[] dictionary)</code> Initializes the <code>Encrypter</code> class with <code>keys, values</code>, and <code>dictionary</code>.</li>
<li><code>String encrypt(String word1)</code> Encrypts <code>word1</code> with the encryption process described above and returns the encrypted string.</li>
<li><code>int decrypt(String word2)</code> Returns the number of possible strings <code>word2</code> could decrypt to that also appear in <code>dictionary</code>.</li>
</ul>
<p><strong>Example 1:</strong></p>
<p><strong>Input</strong> [“Encrypter”, “encrypt”, “decrypt”] [[[‘a’, ‘b’, ‘c’, ‘d’], [“ei”, “zf”, “ei”, “am”], [“abcd”, “acbd”, “adbc”, “badc”, “dacb”, “cadb”, “cbda”, “abad”]], [“abcd”], [“eizfeiam”]]</p>
<p><strong>Output:</strong> [null, “eizfeiam”, 2]</p>
<p><strong>Explanation:</strong> Encrypter encrypter = new Encrypter([[‘a’, ‘b’, ‘c’, ‘d’], [“ei”, “zf”, “ei”, “am”], [“abcd”, “acbd”, “adbc”, “badc”, “dacb”, “cadb”, “cbda”, “abad”]);</p>
<p>encrypter.encrypt(“abcd”); // return “eizfeiam”.
// ‘a’ maps to “ei”, ‘b’ maps to “zf”, ‘c’ maps to “ei”, and ‘d’ maps to “am”.</p>
<p>encrypter.decrypt(“eizfeiam”); // return 2.
// “ei” can map to ‘a’ or ‘c’, “zf” maps to ‘b’, and “am” maps to ‘d’.
// Thus, the possible strings after decryption are “abad”, “cbad”, “abcd”, and “cbcd”.
// 2 of those strings, “abad” and “abcd”, appear in dictionary, so the answer is 2.</p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>1 <= keys.length == values.length <= 26</code></li>
<li><code>values[i].length == 2</code></li>
<li><code>1 <= dictionary.length <= 100</code></li>
<li><code>1 <= dictionary[i].length <= 100</code></li>
<li>All <code>keys[i]</code> and <code>dictionary[i]</code> are <strong>unique</strong>.</li>
<li><code>1 <= word1.length <= 2000</code></li>
<li><code>1 <= word2.length <= 200</code></li>
<li>All <code>word1[i]</code> appear in <code>keys</code>.</li>
<li><code>word2.length</code> is even.</li>
<li><code>keys</code>, <code>values[i]</code>, <code>dictionary[i]</code>, <code>word1</code>, and <code>word2</code> only contain lowercase English letters.</li>
<li>At most <code>200</code> calls will be made to <code>encrypt</code> and <code>decrypt</code> <strong>in total</strong>.</li>
</ul>
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Constructor Summary
Constructors -
Method Summary
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Constructor Details
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Encrypter
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Method Details
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encrypt
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decrypt
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