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Algorithms & data structures easy

Stable merge two lists by custom comparator in Python

Merge two lists into one sorted output using a custom comparator while maintaining the original order of equal elements.

merge stable-sort custom-comparator
Python 
from functools import cmp_to_key

def compare(x, y):
    # Custom comparator: sorts by length first, then by original index for stability
    if len(x) != len(y):
        return len(x) - len(y)
    return 0  # Equal keys preserve original order (stable)

def merge_stable(left, right, cmp_func):
    result = []
    i =…
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