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Algorithms & data structures

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

5 matches

Count Smaller Elements to the Right in Python

Return a list where each index counts how many elements to its right are smaller than that element using a clean O(n²) nested-loop approach.

brute-force nested-loops counting

Python

def count_smaller_elements(arr):
    """
    Return a list where result[i] is the number of elements 
    to the right of arr[i] that are smaller than arr[i].
    """
    result = []
    for i in range(len(arr)):
        count = 0
        for j in range(i + 1, len(arr)):
            if arr[j] < arr[i]:
               …

14 0 Open

Algorithms & data structures easy

How to Build a Coordinate Grid with Nested Loops in Python

Generate a 2D list of (row, col) coordinate pairs using nested loops and return the grid structure.

coordinate grid nested loops 2d list

Python

def build_coordinate_grid(rows, cols):
    """Build a 2D grid of (row, col) coordinates using nested loops."""
    grid = []
    for r in range(rows):
        row = []
        for c in range(cols):
            row.append((r, c))
        grid.append(row)
    return grid


if __name__ == "__main__":
    grid = build_coo…

15 0 Open

Algorithms & data structures easy

How to Generate Fibonacci Sequence in Python

Generate the first n Fibonacci numbers as a list using a simple iterative loop.

fibonacci sequences iteration

Python

def fibonacci(n):
    """Generate the first n terms of the Fibonacci sequence."""
    if n <= 0:
        return []
    seq = [0, 1]
    while len(seq) < n:
        seq.append(seq[-1] + seq[-2])
    return seq[:n]

if __name__ == "__main__":
    n = 10
    result = fibonacci(n)
    print(result)

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 easy

Implement a Stack Using List Push Pop in Python

A minimal Stack class built on a Python list, with push, pop, peek, is_empty, and size methods, including empty-stack guards.

stack data-structures list

Python

class Stack:
    def __init__(self):
        self.items = []

    def push(self, item):
        self.items.append(item)

    def pop(self):
        if self.is_empty():
            raise IndexError("pop from empty stack")
        return self.items.pop()

    def peek(self):
        if self.is_empty():
            raise…

12 0 Open

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