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petertseng merged 3 commits into from
Feb 15, 2019
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saddle-points: Added efficiency notice about vector of vectors #789

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4f5df92
saddle-points: Add efficiency notice about vector of vectors
michalfita Feb 12, 2019
292ed1e
saddle-points: use unambiguous coordinates
bitfield Jan 4, 2019
93dc9a3
saddle-points: use 1-based coordinates
bitfield Jan 5, 2019
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13 changes: 13 additions & 0 deletions exercises/saddle-points/.meta/hints.md
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## Efficiency Notice

This exercise uses a _vector of vectors_ to store the content of matrices. While
this exercise is designed to help students understand basic concepts about
vectors, such as indexing, and that nested data types are legal, _vector of
vectors_ is a suboptimal choice for high-performance matrix algebra and any
similar efficient processing of larger amounts of data.

The detailed explanation of this inefficiency is beyond the scope of this
exercise and this learning track in general. This aspect is known as
[cache locality](https://stackoverflow.com/questions/12065774/why-does-cache-locality-matter-for-array-performance)
and you can find a good introduction to it by clicking that link if you'd like
to learn more about details of a modern computer architecture.
25 changes: 20 additions & 5 deletions exercises/saddle-points/README.md
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Expand Up @@ -5,14 +5,14 @@ Detect saddle points in a matrix.
So say you have a matrix like so:

```text
0 1 2
1 2 3
|---------
0 | 9 8 7
1 | 5 3 2 <--- saddle point at (1,0)
2 | 6 6 7
1 | 9 8 7
2 | 5 3 2 <--- saddle point at column 1, row 2, with value 5
3 | 6 6 7
```

It has a saddle point at (1, 0).
It has a saddle point at column 1, row 2.

It's called a "saddle point" because it is greater than or equal to
every element in its row and less than or equal to every element in
Expand All @@ -28,6 +28,21 @@ The matrix can have a different number of rows and columns (Non square).
Note that you may find other definitions of matrix saddle points online,
but the tests for this exercise follow the above unambiguous definition.

## Efficiency Notice

This exercise uses a _vector of vectors_ to store the content of matrices. While
this exercise is designed to help students understand basic concepts about
vectors, such as indexing, and that nested data types are legal, _vector of
vectors_ is a suboptimal choice for high-performance matrix algebra and any
similar efficient processing of larger amounts of data.

The detailed explanation of this inefficiency is beyond the scope of this
exercise and this learning track in general. This aspect is known as
[cache locality](https://stackoverflow.com/questions/12065774/why-does-cache-locality-matter-for-array-performance)
and you can find a good introduction to it by clicking that link if you'd like
to learn more about details of a modern computer architecture.


## Rust Installation

Refer to the [exercism help page][help-page] for Rust installation and learning
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