Listing 2's implementation runs in o (n) time. I won't prove this, but the running time of Listing 1's naive, recursive implementation is exponential in n.

清单2中的实现所需的时间比清单1短许多，清单2的运行时间为O (n)，而清单1中的递归实现的运行时间是n的指数。

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In Manila, U. N. children's Fund child protection officer Victoria Juat says naive children and parents are lured by an old trick.

联合国儿童基金会驻马尼拉的官员华特说，天真的孩子和父母都上了一个老圈套。

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