Fix sphinx/build_docs warnings for dynamic_programming (#12484)

* Fix sphinx/build_docs warnings for dynamic_programming

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* Fix

* Fix

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
This commit is contained in:
Maxim Smolskiy
2024-12-30 14:52:03 +03:00
committed by GitHub
parent 493a7c153c
commit 7fa9b4bf1b
13 changed files with 294 additions and 285 deletions

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@@ -1,42 +1,48 @@
"""
Find the minimum number of multiplications needed to multiply chain of matrices.
Reference: https://www.geeksforgeeks.org/matrix-chain-multiplication-dp-8/
| Find the minimum number of multiplications needed to multiply chain of matrices.
| Reference: https://www.geeksforgeeks.org/matrix-chain-multiplication-dp-8/
The algorithm has interesting real-world applications. Example:
1. Image transformations in Computer Graphics as images are composed of matrix.
2. Solve complex polynomial equations in the field of algebra using least processing
power.
3. Calculate overall impact of macroeconomic decisions as economic equations involve a
number of variables.
4. Self-driving car navigation can be made more accurate as matrix multiplication can
accurately determine position and orientation of obstacles in short time.
The algorithm has interesting real-world applications.
Python doctests can be run with the following command:
python -m doctest -v matrix_chain_multiply.py
Example:
1. Image transformations in Computer Graphics as images are composed of matrix.
2. Solve complex polynomial equations in the field of algebra using least processing
power.
3. Calculate overall impact of macroeconomic decisions as economic equations involve a
number of variables.
4. Self-driving car navigation can be made more accurate as matrix multiplication can
accurately determine position and orientation of obstacles in short time.
Given a sequence arr[] that represents chain of 2D matrices such that the dimension of
the ith matrix is arr[i-1]*arr[i].
So suppose arr = [40, 20, 30, 10, 30] means we have 4 matrices of dimensions
40*20, 20*30, 30*10 and 10*30.
Python doctests can be run with the following command::
matrix_chain_multiply() returns an integer denoting minimum number of multiplications to
multiply the chain.
python -m doctest -v matrix_chain_multiply.py
Given a sequence ``arr[]`` that represents chain of 2D matrices such that the dimension
of the ``i`` th matrix is ``arr[i-1]*arr[i]``.
So suppose ``arr = [40, 20, 30, 10, 30]`` means we have ``4`` matrices of dimensions
``40*20``, ``20*30``, ``30*10`` and ``10*30``.
``matrix_chain_multiply()`` returns an integer denoting minimum number of
multiplications to multiply the chain.
We do not need to perform actual multiplication here.
We only need to decide the order in which to perform the multiplication.
Hints:
1. Number of multiplications (ie cost) to multiply 2 matrices
of size m*p and p*n is m*p*n.
2. Cost of matrix multiplication is associative ie (M1*M2)*M3 != M1*(M2*M3)
3. Matrix multiplication is not commutative. So, M1*M2 does not mean M2*M1 can be done.
4. To determine the required order, we can try different combinations.
1. Number of multiplications (ie cost) to multiply ``2`` matrices
of size ``m*p`` and ``p*n`` is ``m*p*n``.
2. Cost of matrix multiplication is not associative ie ``(M1*M2)*M3 != M1*(M2*M3)``
3. Matrix multiplication is not commutative. So, ``M1*M2`` does not mean ``M2*M1``
can be done.
4. To determine the required order, we can try different combinations.
So, this problem has overlapping sub-problems and can be solved using recursion.
We use Dynamic Programming for optimal time complexity.
Example input:
arr = [40, 20, 30, 10, 30]
output: 26000
``arr = [40, 20, 30, 10, 30]``
output:
``26000``
"""
from collections.abc import Iterator
@@ -50,25 +56,25 @@ def matrix_chain_multiply(arr: list[int]) -> int:
Find the minimum number of multiplcations required to multiply the chain of matrices
Args:
arr: The input array of integers.
`arr`: The input array of integers.
Returns:
Minimum number of multiplications needed to multiply the chain
Examples:
>>> matrix_chain_multiply([1, 2, 3, 4, 3])
30
>>> matrix_chain_multiply([10])
0
>>> matrix_chain_multiply([10, 20])
0
>>> matrix_chain_multiply([19, 2, 19])
722
>>> matrix_chain_multiply(list(range(1, 100)))
323398
# >>> matrix_chain_multiply(list(range(1, 251)))
# 2626798
>>> matrix_chain_multiply([1, 2, 3, 4, 3])
30
>>> matrix_chain_multiply([10])
0
>>> matrix_chain_multiply([10, 20])
0
>>> matrix_chain_multiply([19, 2, 19])
722
>>> matrix_chain_multiply(list(range(1, 100)))
323398
>>> # matrix_chain_multiply(list(range(1, 251)))
# 2626798
"""
if len(arr) < 2:
return 0
@@ -93,8 +99,10 @@ def matrix_chain_multiply(arr: list[int]) -> int:
def matrix_chain_order(dims: list[int]) -> int:
"""
Source: https://en.wikipedia.org/wiki/Matrix_chain_multiplication
The dynamic programming solution is faster than cached the recursive solution and
can handle larger inputs.
>>> matrix_chain_order([1, 2, 3, 4, 3])
30
>>> matrix_chain_order([10])
@@ -105,8 +113,7 @@ def matrix_chain_order(dims: list[int]) -> int:
722
>>> matrix_chain_order(list(range(1, 100)))
323398
# >>> matrix_chain_order(list(range(1, 251))) # Max before RecursionError is raised
>>> # matrix_chain_order(list(range(1, 251))) # Max before RecursionError is raised
# 2626798
"""