trival，自从写完四等分的问题后，对于这种回朔的问题感觉异常简答。
class Solution { public: void find(int start,int sum, int target,vector<int>& candidates,vector<int>& temp,set<vector<int>>& result) { if(sum==target) result.insert(temp); else if(sum<target) { for(int i=start;i<candidates.size();i++) { temp.push_back(candidates[i]); find(i+1,sum+candidates[i],target,candidates,temp,result); temp.pop_back(); } } else{} return; } vector<vector<int>> combinationSum2(vector<int>& candidates, int target) { sort(candidates.begin(),candidates.end()); vector<int> temp; set<vector<int>> result; find(0,0,target,candidates,temp,result); vector<vector<int>> resultFinal; for(set<vector<int>>::iterator it=result.begin();it!=result.end();it++) resultFinal.push_back(*it); return resultFinal; } };