94 lines
2.6 KiB
Markdown
94 lines
2.6 KiB
Markdown
---
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title: Direct Addressing
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TARGET DECK: Obsidian::STEM
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FILE TAGS: hashing::direct
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tags:
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- hashing
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---
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## Overview
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Given a universe of keys $U = \{0, 1, \ldots, m - 1\}$, a **direct-address table** has $m$ **slots**. Each slot corresponds to a key in universe $U$.
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%%ANKI
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Basic
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With respect to hashing, what does the "universe" of keys refer to?
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Back: Every potential key that may be inserted into the underlying dictionary.
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Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).
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<!--ID: 1716046153757-->
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END%%
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%%ANKI
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Basic
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Given universe $U$, how many slots must a direct-address table have?
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Back: $|U|$
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Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).
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<!--ID: 1716046153762-->
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END%%
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%%ANKI
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Basic
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What name is given to each position in a direct-address table?
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Back: A slot.
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Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).
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<!--ID: 1716046153766-->
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END%%
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%%ANKI
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Basic
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Given a direct-address table, the element at slot $k$ has what key?
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Back: $k$.
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Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).
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<!--ID: 1716046153770-->
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END%%
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%%ANKI
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Basic
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Given a direct-address table, an element with key $k$ is placed in what slot?
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Back: The $k$th slot.
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Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).
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<!--ID: 1716046153775-->
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END%%
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%%ANKI
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Basic
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Write pseudocode to test membership of $x$ in direct-address table `T[0:m-1]`.
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Back
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```c
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bool membership(T, x) {
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return T[x.key] != NIL;
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}
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```
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Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).
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<!--ID: 1716046153781-->
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END%%
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%%ANKI
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Basic
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Write pseudocode to insert $x$ into direct-address table `T[0:m-1]`.
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Back
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```c
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void insert(T, x) {
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T[x.key] = x;
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}
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```
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Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).
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<!--ID: 1716046153785-->
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END%%
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%%ANKI
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Basic
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Write pseudocode to delete $x$ from direct-address table `T[0:m-1]`.
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Back
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```c
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void delete(T, x) {
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T[x.key] = NIL;
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}
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```
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Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).
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<!--ID: 1716046153789-->
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END%%
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## Bibliography
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* Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022). |