[leetcode 78] Subsets

最新推荐文章于 2025-12-27 20:58:23 发布

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本文介绍了一种生成给定整数集合所有可能子集的算法。该算法确保子集中元素按非递减顺序排列且不包含重复子集。通过深度优先搜索实现，详细展示了如何为输入[1,2,3]生成所有子集。

Given a set of distinct integers, S, return all possible subsets.

Note:

Elements in a subset must be in non-descending order.
The solution set must not contain duplicate subsets.

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

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

class Solution {
public:
    vector<vector<int> > subsets(vector<int> &S) {
        sort(S.begin(), S.end());
        vector<vector<int> > res;
        vector<int> path;
        dfs(S, 0, path, res);
        return res;
        
    }
    void dfs(const vector<int> &s, int start, vector<int> &path, vector<vector<int> > &res) {
        if (start == s.size()) {
            res.push_back(path);
            return ;
        }
        for (int i = start; i < s.size(); i++) {
            //dfs(s, i+1, path, res);
            path.push_back(s[i]);
            dfs(s, i+1, path, res);
            path.pop_back();
        }
        res.push_back(path);
        return ;
    }
};