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Algorithms & data structures

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

3 matches

How to Combine filter and map with a List Comprehension in Python

This Python code demonstrates how to combine filtering and mapping in a single list comprehension and shows the equivalent filter() and map() approach.

list-comprehension filter map

Python

def square(x):
    return x * x

def is_even(x):
    return x % 2 == 0

numbers = [1, 2, 3, 4, 5, 6, 7, 8]

result = [square(x) for x in numbers if is_even(x)]

print(f"Original numbers: {numbers}")
print(f"Squares of even numbers: {result}")

# Combined filter + map equivalent
filtered = filter(is_even, numbers)
mapp…

13 0 Open

Algorithms & data structures easy

How to Map Strings to Uppercase in Python

Loops through a list of strings and builds a new list with each string converted to uppercase.

string loop uppercase

Python

strings = ["hello", "world", "python", "skillset"]

uppercased = []
for s in strings:
    uppercased.append(s.upper())

print(uppercased)

15 0 Open

Algorithms & data structures medium

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

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