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27 matches

Segregate Negative Numbers Before Positives in Python

Reorders a list so all negative numbers appear before non-negative numbers while preserving the original relative order of elements.

lists partition stability

Python

def segregate_negatives(numbers):
    """Segregate negatives before positives without altering relative order."""
    negatives = [n for n in numbers if n < 0]
    positives = [n for n in numbers if n >= 0]
    return negatives + positives


if __name__ == "__main__":
    sample = [3, -1, 4, -5, 2, -9, 0]
    result =…

14 0 Open

Algorithms & data structures medium

Set Matrix Zeroes in Python: Markers List Grid Demo

Given a matrix, this code finds all rows and columns that contain a zero and sets every element in those rows and columns to zero, using boolean marker arrays.

matrix arrays algorithm

Python

def set_zeroes(matrix):
    rows, cols = len(matrix), len(matrix[0])
    row_markers = [False] * rows
    col_markers = [False] * cols

    # First pass: record which rows and columns contain zeros
    for i in range(rows):
        for j in range(cols):
            if matrix[i][j] == 0:
                row_markers[i] …

14 0 Open

Algorithms & data structures easy

Sort Unique Values by Frequency in Python

Count element frequencies with Counter and sort unique values by descending frequency, breaking ties alphabetically.

counter sorting frequency

Python

from collections import Counter

def sort_unique_by_frequency(values):
    counts = Counter(values)
    return sorted(counts.keys(), key=lambda x: (-counts[x], x))

if __name__ == "__main__":
    data = [4, 2, 2, 8, 3, 3, 1, 3, 5, 5, 5, 5, 1]
    result = sort_unique_by_frequency(data)
    print(f"Sorted unique values…

12 0 Open

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