q078_Subsets.java

package leetcode_algorithm;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * Given a set of distinct integers, nums, return all possible subsets.
 * <p>
 * Note: The solution set must not contain duplicate subsets.
 * <p>
 * For example,
 * If nums = [1,2,3], a solution is:
 */

public class q078_Subsets {

    public static void main(String[] args) {
        q078_Subsets solution = new q078_Subsets();
        System.out.println(solution.subsets(new int[]{1, 2, 3}));
    }

    /**
     * j½â·¨1 »ØËÝ·¨
     *
     * @param nums
     * @return
     */
    public List<List<Integer>> subsets(int[] nums) {
        List<List<Integer>> list = new ArrayList<>();
        Arrays.sort(nums);
        backtrack(list, new ArrayList<>(), nums, 0);
        return list;
    }

    private void backtrack(List<List<Integer>> list, List<Integer> tempList, int[] nums, int start) {
        list.add(new ArrayList<>(tempList));
        for (int i = start; i < nums.length; i++) {
            tempList.add(nums[i]);
            backtrack(list, tempList, nums, i + 1);
            tempList.remove(tempList.size() - 1);
        }
    }
}