45 lines
911 B
Python
45 lines
911 B
Python
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"""
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递归(recursion)
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"""
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def fac(num):
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"""求阶乘"""
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if num in (0, 1):
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return 1
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return num * fac(num - 1)
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# 动态规划 - 把求解问题的中间结果保存起来
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# 这种算法适合求解有最优子结构的问题或子问题会重复求解的问题
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def fib(num, temp={}):
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"""计算斐波拉切数"""
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# 递归的两个要素
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# 收敛条件 - 什么时候结束递归
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if num in (1, 2):
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return 1
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# 递归公式 - 降低问题的求解难度
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try:
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return temp[num]
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except KeyError:
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temp[num] = fib(num - 1) + fib(num - 2)
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return temp[num]
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def fib2(total):
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"""斐波拉切数列生成器"""
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num1, num2 = 0, 1
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for _ in range(total):
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num1, num2 = num2, num1 + num2
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yield num1
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def main():
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"""主函数"""
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for num in fib2(120):
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print(num)
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if __name__ == '__main__':
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main()
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