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22 lines
566 B
HTML
22 lines
566 B
HTML
<p>A child is running up a staircase with n steps and can hop either 1 step, 2 steps, or 3 steps at a time. Implement a method to count how many possible ways the child can run up the stairs. The result may be large, so return it modulo 1000000007.</p>
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<p><strong>Example1:</strong></p>
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<pre>
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<strong> Input</strong>: n = 3
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<strong> Output</strong>: 4
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</pre>
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<p><strong>Example2:</strong></p>
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<pre>
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<strong> Input</strong>: n = 5
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<strong> Output</strong>: 13
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</pre>
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<p><strong>Note:</strong></p>
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<ol>
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<li><code>1 <= n <= 1000000</code></li>
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</ol>
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