docs: add complexity notes to Strassen algorithm

[shivansh31414]

Describe your change:

improved the docstrings with complexity notes,

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes adding better docstring explaining Strassen’s complexity: #14084

[harshadtech22]

def partition(arr: list, low: int, high: int) -> int:
pivot = arr[high]
i = low - 1
for j in range(low, high):
# Using >= sorts the array in descending order
if arr[j] >= pivot:
i += 1
arr[i], arr[j] = arr[j], arr[i]
arr[i + 1], arr[high] = arr[high], arr[i + 1]
return i + 1

def kth_largest_element(arr: list, position: int) -> int:
if not arr:
return -1 # Match your specific doctest requirement

if not isinstance(position, int):
    raise ValueError("The position should be an integer")

if not 1 <= position <= len(arr):
    raise ValueError("Invalid value of 'position'")

# Create a copy if you don't want to mutate the original list
nums = list(arr) 
low, high = 0, len(nums) - 1

while low <= high:
    pivot_index = partition(nums, low, high)
    
    # Since we partition in descending order:
    # 1st largest (position 1) will be at index 0
    if pivot_index == position - 1:
        return nums[pivot_index]
    elif pivot_index > position - 1:
        high = pivot_index - 1
    else:
        low = pivot_index + 1
        
return -1

you should try this one