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23 lines
588 B
HTML
23 lines
588 B
HTML
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<p>三步问题。有个小孩正在上楼梯，楼梯有n阶台阶，小孩一次可以上1阶、2阶或3阶。实现一种方法，计算小孩有多少种上楼梯的方式。结果可能很大，你需要对结果模1000000007。</p>
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<p> <strong>示例1:</strong></p>
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<pre>
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<strong> 输入</strong>：n = 3
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<strong> 输出</strong>：4
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<strong> 说明</strong>: 有四种走法
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</pre>
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<p> <strong>示例2:</strong></p>
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<pre>
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<strong> 输入</strong>：n = 5
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<strong> 输出</strong>：13
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</pre>
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<p> <strong>提示:</strong></p>
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<ol>
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<li>n范围在[1, 1000000]之间</li>
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</ol>
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