Difference between revisions of "Intermediate C++ Game Programming Tutorial 24"
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* 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] | ||
** <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): | |
+ | ** 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 [https://youtu.be/JlPsCoCO99o?t=7m00s 7:00] | ||
[https://youtu.be/LsjFAx-dG5I Tutorial 24.2] | [https://youtu.be/LsjFAx-dG5I Tutorial 24.2] |
Revision as of 03:00, 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.
Contents
Topics Covered
Part 1
-
std::map
container interface - Binary tree data structure
-
std::map
key requirements (comparison) -
std::map
gotchas (std::remove_if
andconst
keys) -
std::set
-
std::multimap
andstd::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
overstd::unordered_map
Video Timestamp Index
- 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
- [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.