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15 lines
399 B
HTML
15 lines
399 B
HTML
<p>Write a method to count the number of 2s that appear in all the numbers between 0 and n (inclusive).</p>
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<p><strong>Example:</strong></p>
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<pre>
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<strong>Input: </strong>25
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<strong>Output: </strong>9
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<strong>Explanation: </strong>(2, 12, 20, 21, 22, 23, 24, 25)(Note that 22 counts for two 2s.)</pre>
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<p>Note:</p>
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<ul>
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<li><code>n <= 10^9</code></li>
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</ul>
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