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32 lines
1.0 KiB
HTML
32 lines
1.0 KiB
HTML
<p><code>n</code> passengers board an airplane with exactly <code>n</code> seats. The first passenger has lost the ticket and picks a seat randomly. But after that, the rest of the passengers will:</p>
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<ul>
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<li>Take their own seat if it is still available, and</li>
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<li>Pick other seats randomly when they find their seat occupied</li>
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</ul>
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<p>Return <em>the probability that the </em><code>n<sup>th</sup></code><em> person gets his own seat</em>.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> n = 1
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<strong>Output:</strong> 1.00000
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<strong>Explanation: </strong>The first person can only get the first seat.</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> n = 2
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<strong>Output:</strong> 0.50000
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<strong>Explanation: </strong>The second person has a probability of 0.5 to get the second seat (when first person gets the first seat).
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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 <= n <= 10<sup>5</sup></code></li>
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</ul>
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