Java实现-子集

[1,2,3]

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

class Solution {
/**
* @param S: A set of numbers.
* @return: A list of lists. All valid subsets.
*/
public ArrayList<ArrayList<Integer>> subsets(int[] nums) {
// write your code here
Arrays.sort(nums);
ArrayList<ArrayList<Integer>> result=new ArrayList<ArrayList<Integer>>();
ArrayList<Integer> tempList=new ArrayList<Integer>();
backTracking(nums, 0, result, tempList);
return result;
}
private static void backTracking(int[] nums, int start, ArrayList<ArrayList<Integer>> result, ArrayList<Integer> tempList){
result.add(new ArrayList<Integer>(tempList));
for(int i=start;i<nums.length;i++){
tempList.add(nums[i]);
backTracking(nums, i+1, result, tempList);
tempList.remove(tempList.size()-1);
}
}

}