|
马上注册,结交更多好友,享用更多功能^_^
您需要 登录 才可以下载或查看,没有账号?立即注册
x
Maximum product of parts
Let N be a positive integer and let N be split into k equal parts, r = N/k, so that N = r + r + ... + r.
Let P be the product of these parts, P = r × r × ... × r = rk.
For example, if 11 is split into five equal parts, 11 = 2.2 + 2.2 + 2.2 + 2.2 + 2.2, then P = 2.25 = 51.53632.
Let M(N) = Pmax for a given value of N.
It turns out that the maximum for N = 11 is found by splitting eleven into four equal parts which leads to Pmax = (11/4)4; that is, M(11) = 14641/256 = 57.19140625, which is a terminating decimal.
However, for N = 8 the maximum is achieved by splitting it into three equal parts, so M(8) = 512/27, which is a non-terminating decimal.
Let D(N) = N if M(N) is a non-terminating decimal and D(N) = -N if M(N) is a terminating decimal.
For example, ΣD(N) for 5 ≤ N ≤ 100 is 2438.
Find ΣD(N) for 5 ≤ N ≤ 10000.
题目:
N 是一个正整数,然后,将 N 平分成 k 份,r = N/k,则 N = r + r + ... + r。
定义 P 为这些的乘积,即 P = r × r × ... × r = rk。
比如,如果 11 被平分成 5 块的话,11 = 2.2 + 2.2 + 2.2 + 2.2 + 2.2,则 P = 2.25 = 51.53632。
对给定的 N,定义 M(N) = Pmax。
可以证明,对 N=11 时,把它平分成 4 块,可以得到 P 的最大值 Pmax = (11/4)4;也就是说,M(11) = 14641/256 = 57.19140625,是个有限小数。
至于 N=8 时,则是把 8 分成 3 部分时取到 P 的最大值,得到 M(8) = 512/27,这是个无限小数。
如果 M(N) 是无限小数,则定义 D(N) = N ,否则,D(N) = -N。
例如,对于 5 ≤ N ≤ 100 来说, ΣD(N) 是 2438。
请给出 5 ≤ N ≤ 10000 时,ΣD(N) 的值。
|
|