Practice selecting a maximum-size subset whose values are pairwise divisible. Return any optimal membership and explain correctness, including cases with multiple valid answers.
# Return a Largest Pairwise-Divisible Subset
Given a list `nums` of distinct positive integers, return a subset with the greatest possible number of elements such that every pair of its elements divides in at least one direction. For any two selected values `a` and `b`, either `a % b == 0` or `b % a == 0` must hold.
If several maximum-size subsets exist, return any one of them.
### Function
`vector<int> largestDivisibleSubset(vector<int>& nums)`
### Example 1
```text
Input: nums = [2,3,6]
One valid output: [2,6]
```
`[3,6]` is also valid and has the same maximum size. The subset `[2,3,6]` is invalid because neither `2` nor `3` divides the other.
### Example 2
```text
Input: nums = [4,8,16]
Output: [4,8,16]
```
### Constraints
- `1 <= nums.length <= 1000`.
- `1 <= nums[i] <= 2000000000`.
- All values are distinct.
### Clarifications
Return selected values, not their count or indices. Reusing a value is not allowed. A subset has no required display order. Different optimal subsets may have different members; there is no required tie-breaking rule.
### What a Strong Answer Covers
- The condition on every selected pair.
- Why the returned subset has maximum size.
- Single-element inputs and multiple equally good outputs.
- A correctness argument and resource bounds at the stated limits.
### Follow-up Questions
- If two implementations return different subsets for the same input, what would you check to decide whether both are correct without requiring their chosen members or display order to match?
Overview: Practice selecting a maximum-size subset whose values are pairwise divisible. Return any optimal membership and explain correctness, including cases with multiple valid answers.
Given a list nums of distinct positive integers, return a subset with the greatest possible number of elements such that every pair of its elements divides in at least one direction. For any two selected values a and b, either a % b == 0 or b % a == 0 must hold.
If several maximum-size subsets exist, return any one of them.
[3,6] is also valid and has the same maximum size. The subset [2,3,6] is invalid because neither 2 nor 3 divides the other.
Example 2
Input: nums = [4,8,16]
Output: [4,8,16]
Constraints
1 <= nums.length <= 1000
.
1 <= nums[i] <= 2000000000
.
All values are distinct.
Clarifications
Return selected values, not their count or indices. Reusing a value is not allowed. A subset has no required display order. Different optimal subsets may have different members; there is no required tie-breaking rule.
What a Strong Answer Covers Guidance
The condition on every selected pair.
Why the returned subset has maximum size.
Single-element inputs and multiple equally good outputs.
A correctness argument and resource bounds at the stated limits.
Follow-up Questions Guidance
If two implementations return different subsets for the same input, what would you check to decide whether both are correct without requiring their chosen members or display order to match?