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40 lines
1.5 KiB
HTML
40 lines
1.5 KiB
HTML
<p>You are given a string <code>num</code> consisting of digits only.</p>
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<p>Return <em>the <strong>largest palindromic</strong> integer (in the form of a string) that can be formed using digits taken from </em><code>num</code>. It should not contain <strong>leading zeroes</strong>.</p>
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<p><strong>Notes:</strong></p>
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<ul>
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<li>You do <strong>not</strong> need to use all the digits of <code>num</code>, but you must use <strong>at least</strong> one digit.</li>
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<li>The digits can be reordered.</li>
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</ul>
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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> num = "444947137"
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<strong>Output:</strong> "7449447"
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<strong>Explanation:</strong>
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Use the digits "4449477" from "<u><strong>44494</strong></u><u><strong>7</strong></u>13<u><strong>7</strong></u>" to form the palindromic integer "7449447".
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It can be shown that "7449447" is the largest palindromic integer that can be formed.
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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> num = "00009"
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<strong>Output:</strong> "9"
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<strong>Explanation:</strong>
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It can be shown that "9" is the largest palindromic integer that can be formed.
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Note that the integer returned should not contain leading zeroes.
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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 <= num.length <= 10<sup>5</sup></code></li>
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<li><code>num</code> consists of digits.</li>
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</ul>
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