LeetCode - Subsets
Problem description
Given a set of distinct integers, nums, return all possible subsets (the power set).
Note: The solution set must not contain duplicate subsets.
Example:
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Input: nums = [1,2,3]
Output:
[
[3],
[1],
[2],
[1,2,3],
[1,3],
[2,3],
[1,2],
[]
]
Analysis
The general idea is to use backtrack.
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class Solution {
public List<List<Integer>> subsets(int[] nums) {
List<List<Integer>> res = new ArrayList<>();
backtrack(res, new ArrayList<>(), 0, nums);
return res;
}
void backtrack(List<List<Integer>> res, List<Integer> list, int start, int[] nums){
if (start > nums.length){
return;
}
res.add(new ArrayList(list));
for (int i = start; i < nums.length; i++){
list.add(nums[i]);
backtrack(res, list, i+1, nums);
list.remove(list.size() -1 );
}
}
}