78. subset
跟昨天那题一样ㄚ
昨天用recursion
好久之前用过iterative 摆摆位子
这次试着用bit mask先选好位子再来放
class Solution {
public:
vector<vector<int>> subsets(vector<int>& nums) {
vector<vector<int>> res;
int n = nums.size();
for(int i = 0; i < (1 << n); i++){
vector < int> t;
for(int j = 0; j < n; j++){
if( (1 << j) & i){
t.push_back(nums[j]);
}
}
res.push_back(t);
}
return res;
}
};