mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-18 01:00:15 +00:00
943e03fc54
* Minor changes due to precommit * Update optimal_merge_pattern.py Co-authored-by: Christian Clauss <cclauss@me.com>
57 lines
1.6 KiB
Python
57 lines
1.6 KiB
Python
"""
|
|
This is a pure Python implementation of the greedy-merge-sort algorithm
|
|
reference: https://www.geeksforgeeks.org/optimal-file-merge-patterns/
|
|
|
|
For doctests run following command:
|
|
python3 -m doctest -v greedy_merge_sort.py
|
|
|
|
Objective
|
|
Merge a set of sorted files of different length into a single sorted file.
|
|
We need to find an optimal solution, where the resultant file
|
|
will be generated in minimum time.
|
|
|
|
Approach
|
|
If the number of sorted files are given, there are many ways
|
|
to merge them into a single sorted file.
|
|
This merge can be performed pair wise.
|
|
To merge a m-record file and a n-record file requires possibly m+n record moves
|
|
the optimal choice being,
|
|
merge the two smallest files together at each step (greedy approach).
|
|
"""
|
|
|
|
|
|
def optimal_merge_pattern(files: list) -> float:
|
|
"""Function to merge all the files with optimum cost
|
|
|
|
Args:
|
|
files [list]: A list of sizes of different files to be merged
|
|
|
|
Returns:
|
|
optimal_merge_cost [int]: Optimal cost to merge all those files
|
|
|
|
Examples:
|
|
>>> optimal_merge_pattern([2, 3, 4])
|
|
14
|
|
>>> optimal_merge_pattern([5, 10, 20, 30, 30])
|
|
205
|
|
>>> optimal_merge_pattern([8, 8, 8, 8, 8])
|
|
96
|
|
"""
|
|
optimal_merge_cost = 0
|
|
while len(files) > 1:
|
|
temp = 0
|
|
# Consider two files with minimum cost to be merged
|
|
for i in range(2):
|
|
min_index = files.index(min(files))
|
|
temp += files[min_index]
|
|
files.pop(min_index)
|
|
files.append(temp)
|
|
optimal_merge_cost += temp
|
|
return optimal_merge_cost
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|