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Algorithms & data structures

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4 matches

How to Rotate an Array by k Steps in Python

This code rotates a list to the right by k positions using modulo arithmetic to handle k larger than the list length.

def rotate_array(nums, k):
    if not nums:
        return []
    n = len(nums)
    k = k % n
    return nums[-k:] + nums[:-k] if k else nums[:]

if __name__ == "__main__":
    arr = [1, 2, 3, 4, 5, 6]
    k = 2
    result = rotate_array(arr, k)
    print(f"Original: {arr}")
    print(f"Rotated by {k}: {result}")

13 0 Open

Algorithms & data structures easy

How to partition a list into n nearly equal parts in Python

Divide a list into n contiguous chunks of nearly equal size using an average-length calculation that distributes the remainder evenly.

partitioning chunks slicing

Python

def partition(lst, n):
    """Partition a list into n nearly equal contiguous parts."""
    if n <= 0:
        raise ValueError("n must be positive")
    if not lst:
        return [[] for _ in range(n)]
    
    parts = []
    avg = len(lst) / n
    last_idx = 0.0
    
    while last_idx < len(lst):
        end_idx =…

14 0 Open

Algorithms & data structures easy

Remove item at index without pop in Python

Remove an item at a given index from a list without using pop by slicing the list around the index.

list slicing algorithms

Python

def remove_at_index(lst, index):
    """Remove item at index and return the new list."""
    if index < 0 or index >= len(lst):
        raise IndexError("Index out of range")
    return lst[:index] + lst[index + 1:]


if __name__ == "__main__":
    items = [10, 20, 30, 40, 50]
    result = remove_at_index(items, 2)
  …

12 0 Open

Algorithms & data structures easy

Reorder a List by Odd Even Indices in Python

Splits a list into two sublists based on 1-based index parity, then concatenates odd-indexed elements before even-indexed ones.

list indices reorder

Python

def reorder_by_odd_even(items):
    """Reorders a list so that elements at odd indices come first,
    followed by elements at even indices (1-based).
    
    Example: [0,1,2,3,4,5,6] -> [1,3,5,0,2,4,6]
    """
    odds = [items[i] for i in range(1, len(items), 2)]
    evens = [items[i] for i in range(0, len(items), …

18 0 Open

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