#0246

Subsets With Duplicates

MediumDSA28 min20 XP

Problem

Return all unique subsets of nums. Each subset and the final output should be sorted lexicographically.

Why This Matters

This problem teaches the backtracking duplicate-skip rule that also appears in permutations and combination-sum variants.

Function Signature

def subsets_with_dup(nums):

Examples

Example 1

Inputnums = [1, 2, 2]

Output[[], [1], [1, 2], [1, 2, 2], [2], [2, 2]]

The second 2 is not allowed to start the same branch twice.

Constraints

Return the exact requested value.
Handle empty or small inputs when the prompt allows them.
Prefer the target DSA pattern over brute force when the input can grow.

CodePython

def subsets_with_dup(nums):
    """
    Input example: nums = [1, 2, 2]
    Return: [[], [1], [1, 2], [1, 2, 2], [2], [2, 2]]
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return []

def subsets_with_dup(nums):
    """
    Input example: nums = [1, 2, 2]
    Return: [[], [1], [1, 2], [1, 2, 2], [2], [2, 2]]
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return []

Visible browser tests run here when available.

Testcases2 visible / 3 hidden categories

One duplicate

Input[1, 2, 2]

Expected[[], [1], [1, 2], [1, 2, 2], [2], [2, 2]]

All unique subsets are returned once.

All same

Input[2, 2]

Expected[[], [2], [2, 2]]

Only three unique subsets exist.

Hidden Test Categories

empty inputthree duplicatesunsorted input