Subsets

最新推荐文章于 2021-01-18 21:21:53 发布

原创最新推荐文章于 2021-01-18 21:21:53 发布 · 479 阅读

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class Solution {
public:
    vector<vector<int> > subsets(vector<int> &S) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        sort(S.begin(), S.end());
        vector<vector<int> > res(1);
        for (int i=0; i<S.size(); i++) {
            int j=res.size()-1;
            for (; j>=0; j--) {
                res.push_back(res[j]);
                res[j].push_back(S[i]);
            }
        }
        return res;
    }
};

dfs:

class Solution {
public:
    void dfs(vector<int> &S, int d, vector<vector<int> > &res, vector<int> &cur) {
        if (d==S.size()) return;
        for (int i=d; i<S.size(); i++) {
            cur.push_back(S[i]);
            res.push_back(cur);
            dfs(S,i+1,res,cur);
            cur.pop_back();
        }
    }
    vector<vector<int> > subsets(vector<int> &S) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        vector<vector<int> > res;
        if (S.size()==0) return res;
        vector<int> cur;
        res.push_back(cur);
        sort(S.begin(), S.end());
        dfs(S, 0, res, cur);
        return res;
    }
};

class Solution {
public:
    vector<vector<int> > subsetsWithDup(vector<int> &S) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        sort(S.begin(), S.end());
        vector<vector<int> > res(1);
        int i=0,j=0;
        for (;i<S.size(); i++) {
            int len=res.size();
            for(;j<len; j++) {
                res.push_back(res[j]);
                res.back().push_back(S[i]);
            }
            if (S[i]==S[i+1]) {
                j=len;
            }else {
                j=0;
            }
        }
        return res;
    }
};

dfs:

class Solution {
public:
    void dfs(vector<int> &S, int d, vector<vector<int>> &res, vector<int> &cur) {
        if (d==S.size()) return;
        for (int i=d; i<S.size(); i++) {
            if (i>d && S[i]==S[i-1]) continue;
            cur.push_back(S[i]);
            res.push_back(cur);
            dfs(S,i+1,res,cur);
            cur.pop_back();
        }
    } 
    vector<vector<int> > subsetsWithDup(vector<int> &S) {
        vector<vector<int> > res;
        if (S.size()==0) return res;
        vector<int> cur;
        res.push_back(cur);
        sort(S.begin(),S.end());
        dfs(S,0,res,cur);
        return res;
    }
};