mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-30 16:31:08 +00:00
3d0a409ce1
* Improved Equilibrium Index of an Array.
This is the modifications made to the original code:
1. Create Doctest Instructions: Python "doctest" can be executed by running the following command: python -m doctest -v equilibrium_index.py.
2. Deleted Argument {size}: Deleted the `size` argument because `len(arr)} allows the array's length to be determined inside the function, simplifying and improving the readability of the function signature.
3. Used {enumerate}: To improve code readability and indicate that we're working with element-index pairs, we iterated through the array using both elements and their indices using the `enumerate` function.
4. Optimized the Loop: To prevent pointless additions, the loop was improved by initializing {left_sum} with the value of the first element (arr[0]). Furthermore, since the beginning and last items (0 and size - 1) cannot be equilibrium indices, there is no need to check them, saving further computations.
* [pre-commit.ci] auto fixes from pre-commit.com hooks
for more information, see https://pre-commit.ci
---------
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
59 lines
1.3 KiB
Python
59 lines
1.3 KiB
Python
"""
|
|
Find the Equilibrium Index of an Array.
|
|
Reference: https://www.geeksforgeeks.org/equilibrium-index-of-an-array/
|
|
|
|
Python doctest can be run with the following command:
|
|
python -m doctest -v equilibrium_index.py
|
|
|
|
Given a sequence arr[] of size n, this function returns
|
|
an equilibrium index (if any) or -1 if no equilibrium index exists.
|
|
|
|
The equilibrium index of an array is an index such that the sum of
|
|
elements at lower indexes is equal to the sum of elements at higher indexes.
|
|
|
|
|
|
|
|
Example Input:
|
|
arr = [-7, 1, 5, 2, -4, 3, 0]
|
|
Output: 3
|
|
|
|
"""
|
|
|
|
|
|
def equilibrium_index(arr: list[int]) -> int:
|
|
"""
|
|
Find the equilibrium index of an array.
|
|
|
|
Args:
|
|
arr (list[int]): The input array of integers.
|
|
|
|
Returns:
|
|
int: The equilibrium index or -1 if no equilibrium index exists.
|
|
|
|
Examples:
|
|
>>> equilibrium_index([-7, 1, 5, 2, -4, 3, 0])
|
|
3
|
|
>>> equilibrium_index([1, 2, 3, 4, 5])
|
|
-1
|
|
>>> equilibrium_index([1, 1, 1, 1, 1])
|
|
2
|
|
>>> equilibrium_index([2, 4, 6, 8, 10, 3])
|
|
-1
|
|
"""
|
|
total_sum = sum(arr)
|
|
left_sum = 0
|
|
|
|
for i, value in enumerate(arr):
|
|
total_sum -= value
|
|
if left_sum == total_sum:
|
|
return i
|
|
left_sum += value
|
|
|
|
return -1
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|