Difference between revisions of "Intermediate C++ Game Programming Tutorial 24"

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(→‎Video Timestamp Index)
(→‎Video Timestamp Index)
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== Video Timestamp Index ==
 
== Video Timestamp Index ==
 
[https://youtu.be/JlPsCoCO99o Tutorial 24.1]
 
[https://youtu.be/JlPsCoCO99o Tutorial 24.1]
 +
<div class="mw-collapsible mw-collapsed"><br />
 
* The <code>std::map<KeyType,ValueType></code> class [https://youtu.be/JlPsCoCO99o?t=0m46s 0:46]
 
* The <code>std::map<KeyType,ValueType></code> class [https://youtu.be/JlPsCoCO99o?t=0m46s 0:46]
 +
<div class="mw-collapsible-content">
 
** Maps consist of keys to lookup (associated with) values
 
** Maps consist of keys to lookup (associated with) values
 
** <code>map.insert( {key,value} )</code> to insert (key,value) pairs
 
** <code>map.insert( {key,value} )</code> to insert (key,value) pairs
 
** <code>map[key]</code> returns a reference to the ValueType for a KeyType
 
** <code>map[key]</code> returns a reference to the ValueType for a KeyType
 +
</div>
 
* The Binary tree data structure [https://youtu.be/JlPsCoCO99o?t=2m46s 2:46]
 
* The Binary tree data structure [https://youtu.be/JlPsCoCO99o?t=2m46s 2:46]
 +
<div class="mw-collapsible-content">
 
** <code>std::map</code> performs lookup in O(log(n)), it uses a Binary tree data structure
 
** <code>std::map</code> performs lookup in O(log(n)), it uses a Binary tree data structure
 
** Key properties of a Binary Tree (BT):
 
** Key properties of a Binary Tree (BT):
−
** Nodes can have at most 2 children (hence: binary)
+
*:- Nodes can have at most 2 children (hence: binary)
−
** Each left child is smaller and each right child is larger than its parent
+
*:- Each left child is smaller and each right child is larger than its parent
−
** Insertion is done by navigating the tree along a route Left for smaller, Right for larger such that the order property always holds  
+
*:- Insertion is done by navigating the tree along a route Left for smaller, Right for larger such that the order property always holds  
 
** The big advantage of the BT properties is that retrieval is very fast
 
** The big advantage of the BT properties is that retrieval is very fast
 +
</div>
 
* The beaty of std::map is that we don't have to implement any of this; it's all there in the STL [https://youtu.be/JlPsCoCO99o?t=7m00s 7:00]
 
* The beaty of std::map is that we don't have to implement any of this; it's all there in the STL [https://youtu.be/JlPsCoCO99o?t=7m00s 7:00]
 +
</div>
  
 
[https://youtu.be/LsjFAx-dG5I Tutorial 24.2]
 
[https://youtu.be/LsjFAx-dG5I Tutorial 24.2]

Revision as of 03:03, 20 January 2020

Associative containers are super useful, both as a convenient fast way to create dictionary or mapping for real-world problems like managing game resources, and as a data structure to help solve more abstract algorithmic computer science problems. And hash tables are fast as balls.

Topics Covered

Part 1

  • std::map container interface
  • Binary tree data structure
  • std::map key requirements (comparison)
  • std::map gotchas (std::remove_if and const keys)
  • std::set
  • std::multimap and std::multiset

Part 2

  • Hash table performance vs. binary tree performance
  • Hash table data structure
  • std::unordered_map key requirements
  • Hash combining
  • std::unordered_map bucket interface and hashing policy
  • When to choose std::map over std::unordered_map

Video Timestamp Index

Tutorial 24.1


  • The std::map<KeyType,ValueType> class 0:46
    • Maps consist of keys to lookup (associated with) values
    • map.insert( {key,value} ) to insert (key,value) pairs
    • map[key] returns a reference to the ValueType for a KeyType
  • The Binary tree data structure 2:46
    • std::map performs lookup in O(log(n)), it uses a Binary tree data structure
    • Key properties of a Binary Tree (BT):
    - Nodes can have at most 2 children (hence: binary)
    - Each left child is smaller and each right child is larger than its parent
    - Insertion is done by navigating the tree along a route Left for smaller, Right for larger such that the order property always holds
    • The big advantage of the BT properties is that retrieval is very fast
  • The beaty of std::map is that we don't have to implement any of this; it's all there in the STL 7:00

Tutorial 24.2

  • [WORK-IN-PROGRESS]

Homework Assignment

The homework for this video is to enable use of a custom datatype in unordered_map hashing over multiple (4) members of that datatype. The solution video is here.

Supplementary Link

See also

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