LeetCode 78. Subsets

78. Subsets
Given a set of distinct integers, nums, return all possible subsets.

Note: The solution set must not contain duplicate subsets.

For example,
If nums = [1,2,3], a solution is:

[
[3],
[1],
[2],
[1,2,3],
[1,3],
[2,3],
[1,2],
[]
]

题目大意：给一个集合nums，求nums的所有子集集合～
分析：用位运算，j从0到maxn变化，每一次计算j移动i位后最后一位是否为1，如果为1就将nums[i]的值放入result[j]～

class Solution {public:    vector<vector<int>> subsets(vector<int>& nums) {        int len = nums.size();        int maxn = pow(2, len);        vector<vector<int>> result(maxn);        for (int i = 0; i < len; i++) {            for (int j = 0; j < maxn; j++) {                if ((j >> i) & 1)                    result[j].push_back(nums[i]);            }        }        return result;    }};