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Algorithms & data structures

Classic patterns — search, sort, stacks, queues, and practical complexity-aware code.

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Implement Insert Delete GetRandom O(1) in Python

Build a RandomizedSet class that supports insert, delete, and get_random in average O(1) time using a list and a dictionary mapping values to indices.

randomized-set o1-lookup hash-map

Python

import random

class RandomizedSet:
    def __init__(self):
        self.values = []
        self.index_map = {}

    def insert(self, val):
        if val in self.index_map:
            return False
        self.index_map[val] = len(self.values)
        self.values.append(val)
        return True

    def delete(self…

12 0 Open

Algorithms & data structures easy

Insert Multiple Values Into a Sorted List in Python

Insert multiple values into an already-sorted list while keeping it sorted using the bisect.insort function.

bisect sorted-list insertion

Python

import bisect

def insert_sorted(sorted_list, values):
    for value in values:
        bisect.insort(sorted_list, value)
    return sorted_list

if __name__ == "__main__":
    original = [1, 3, 5, 7, 9]
    new_values = [4, 6, 2, 8, 0]
    result = insert_sorted(original, new_values)
    print(f"Original: {original}"…

14 0 Open

Algorithms & data structures easy

Insert an Element Every n Positions in Python

Insert a given element before or after every n-th position in a Python list, returning a new list with the placements applied.

list-manipulation insertion algorithms

Python

def insert_every_n(seq, element, n, position="after"):
    """Insert an element before or after every n-th position in a list.

    Args:
        seq: Input list
        element: Element to insert
        n: Insert every n positions (n > 0)
        position: 'before' or 'after' (default: 'after')
    Returns:
        …

13 0 Open

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