taocp,顺序分配问题

发布于 2024-07-27 01:52:20 字数 554 浏览 3 评论 0原文

我在工作 tacop 2.2.2 顺序分配、重新打包第 247 页的内存部分时遇到了一些问题。

主题是有 n 个堆栈共享公共区域位置 L0 < L< LX, 最初我们设置 BASE[j] = TOP[j] = L0 为 1 <= j <= n

目标是在插入或删除元素时发生溢出 to stack i,如何重新打包内存。 (通过从堆栈中取出一些来为堆栈 i 腾出空间 尚未填满的表)。

A)。 找到 i < 的最小 k k< n 且 TOP[k] < BASE[k+1],如果有这样的 k 存在。 将事情提升一个档次, 设置内容(L+1)-> CONTENTS(L),对于 TOP[k] >= L > 基数[i+1] 最后, 设置 BASE[j] -> BASE[j] + 1, TOP[j] -> TOP[j] + 1,对于 i < j< k

这是我的问题:

他们如何找到尚未填充的堆栈? 堆栈 k? 为什么选择最小的k?

i've run into few problems while working tacop 2.2.2 sequential allocations, repacking memory section at page 247.

the subject is there are n stacks sharing a common area locations L0 < L < LX,
initially we set BASE[j] = TOP[j] = L0 for 1 <= j <= n

the goal is when overflow occurs while inserting or deleting elements with respect
to stack i, how to repack memory. (making room for stack i by taking some away from
tables that aren't yet filled).

a). find the smallest k for which i < k < n and TOP[k] < BASE[k+1], if any such k
exists. move things up one notch,
Set CONTENTS(L+1) -> CONTENTS(L), for TOP[k] >= L > BASE[i+1]
finally,
Set BASE[j] -> BASE[j] + 1, TOP[j] -> TOP[j] + 1, for i < j < k

here's my questions:

how do they find the stack that aren't yet to be filled? stack k? and why chose the smallest k?

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画中仙 2024-08-03 01:52:20

要找到尚未填满的堆栈,使用的基本思想是:

堆栈k未满<==> <代码>TOP[k] < 基数[k+1]

算法第一步中的循环从 i+1n 运行 k 来查找第一个满足此条件的k

另请注意,最初通过设置 BASE[n] = TOP[n] = L0 和 BASE[n,将所有空间分配给最后一个(第 n 个)堆栈+1]=LInfty。 因此,除非所有“更高”的堆栈都已被填满,否则我们将找到这样一个k

你的第二个问题(为什么选择最小的k?)更容易回答:第247页的算法只是重新打包的一种方法简单 一个。 正如 Knuth 在算法文本上方的段落中提到的:

有几种重新包装的方法可供选择; ...
我们将从提供最简单的方法开始,
然后将考虑一些替代方案。

后来,Knuth 描述了一种重新打包方法,该方法考虑了早期的重新打包,使该过程具有一定的适应性。

To find the stack that isn't yet filled, the basic idea used is the fact:

Stack k is not full <==> TOP[k] < BASE[k+1]

The loop in the first step of the algorithm runs k from i+1 to n to find the first k that satisfies this condition.

Also note that initially all space is given to the last, nth, stack by setting BASE[n] = TOP[n] = L0 and BASE[n+1]=LInfty. So unless all "higher" stacks have been filled, we will find such a k.

Your second question (Why choose the smallest such k?) is more easily answered: The algorithm on Page 247 is just one way of repacking and a simple one at that. As Knuth mentions in the paragraph just above the text of the algorithm:

Several ways to do the repacking suggest themselves; ...
We will start by giving the simplest of the methods,
and will then consider some of the alternatives.

Later, Knuth describes a repacking approach that takes into account the earlier repacking, making the process somewhat adaptive.

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