data_structures.arrays.equilibrium_index_in_array

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_in_array.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

Functions

equilibrium_index(→ int)

Find the equilibrium index of an array.

Module Contents

data_structures.arrays.equilibrium_index_in_array.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