title
Given a set of distinct integers, nums, return all possible subsets (the power set).
Note: The solution set must not contain duplicate subsets.
Example:
Input: nums = [1,2,3]
Output:
[
[3],
[1],
[2],
[1,2,3],
[1,3],
[2,3],
[1,2],
[]
]
solution
排列组合求子集问题
class Solution {
public:
void backtracking(vector<vector<int>> &res, vector<int> t, vector<int>& nums, int start,int n,vector<bool> &visit) {
if (t.size() == n) {
res.push_back(t);
return;
}
for (int i = start; i < nums.size(); i++) {
if (i != 0 && nums[i] == nums[i - 1] && !visit[i - 1]) {
continue;
}
t.push_back(nums[i]);
visit[i] = true;
backtracking(res, t, nums, i + 1, n, visit);
visit[i] = false;
t.pop_back();
}
}
vector<vector<int>> subsets(vector<int>& nums) {
vector<vector<int>> res;
vector<bool> visit(nums.size(), false);
vector<int> t;
for (int i = 0; i <= nums.size(); i++) {
backtracking(res, t, nums,0,i, visit);
}
return res;
}
};