78. Subsets¶

Edited by Charles

Medium · Python · Backtrack

Problem

The official page contains the problem statement, examples, and constraints.

Explanation, examples & other approaches

Core idea

the solution does not necessarily need a terminal condition, since the for loop stops at the last element of nums. path is initiated as [].

result.append(path[:])

Original study notes follow, including intermediate snippets and earlier attempts.

Note:

the solution does not necessarily need a terminal condition, since the for loop stops at the last element of nums.
path is initiated as [].
```
result.append(path[:])
```
ensures [] and nums itself are appended to result.

Study record

Field	Value
Attempts	1
Mastery	❚
The Latest Attempt	January 24, 2026

Python solution¶

class Solution:
    def subsets(self, nums: List[int]) -> List[List[int]]:
        result = []
        self.backtrack(nums, 0, [], result)
        return result

    def backtrack(self, nums, startIndex, path, result):
        # This step ensures [] and nums itself are appended to the result.
        result.append(path[:])

        for i in range(startIndex, len(nums)):
            path.append(nums[i])
            self.backtrack(nums, i + 1, path, result)
            path.pop()

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