p78

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LeetCode p78 Subsets 题解

1.题目：

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],
[]
]

题意：

返回一个数组所有的子集。

2.解题思路:

dp

3.代码

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public class Solution {
    public List<List<Integer>> subsets(int[] nums) {
        List<List<Integer>> ans = new ArrayList<List<Integer>>();
		List<Integer> list = new ArrayList<Integer>();
		dp(ans, nums, 0, list);
		return ans;
    }
    public void dp(List<List<Integer>> ans, int[] nums, int start,
			List<Integer> list) {
		if (start > nums.length)
			return;
		ans.add(new ArrayList<Integer>(list));
		for (int i = start; i < nums.length; i++) {
			list.add(nums[i]);
			dp(ans, nums, i + 1, list);
			list.remove(list.size() - 1);

		}
	}
}

4.一些总结：