[Leetcode] Combinations

Problem Description:

Given-integers n and K, return all possible combinations ofK numbers out of 1 ... n.

For example,
If N = 4 and k = 2, a solution is:

[  [2,4],  [3,4], [  2,3],  [up],  [1,3],  [1,4],]

Basic idea:

Backtracking method

Code:

 Vector<int> record;    C + + vector<vector<int> >result;    set<vector<int> > MySet;        int knum = 0;        void Addsolution () {vector<int> tmp (Record.begin (), Record.end ());        Sort (Tmp.begin (), Tmp.end ());            if (Myset.find (tmp) = = Myset.end ()) {result.push_back (TMP);           Myset.insert (TMP); }} void Subcombinationsum (vector<int> &cadidates,int bpos,vector<int> &base, int k) {if (        Knum = = k) {addsolution ();        } int size = Cadidates.size ();                            for (int i = BPOs; i < size; i++) {if (base[i] = = 1) continue;            Record.push_back (Cadidates[i]);            Base[i] = 1;            knum++; Subcombinationsum (Cadidates,<span style= "color: #FF0000;"  &GT;&LT;STRONG&GT;I+1&LT;/STRONG&GT;&LT;/SPAN&GT;,BASE,K);            I+1 avoid repeating record.pop_back ();            Base[i] = 0; Knum--;        }} vector<vector<int> > combine (int n, int k) {vector<int> candidates (n);        for (int i = 0; i < n; i++) candidates[i] = i+1;        Vector<int> Base (candidates.size (), 0);        Subcombinationsum (CANDIDATES,0,BASE,K);    return result; }

[Leetcode] Combinations