LeetCode 40. Combination Sum II

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

Each number in C may only be used once in the combination.

Note:

• All numbers (including target) will be positive integers.
• The solution set must not contain duplicate combinations.

For example, given candidate set [10, 1, 2, 7, 6, 1, 5] and target 8, 
A solution set is: 

[
  [1, 7],
  [1, 2, 5],
  [2, 6],
  [1, 1, 6]
]

先对所有数字排序,将结果放入set集合中（为了避免重复），将结果比target大的数都return（避免超时），最后将结果存放到二维数组中。

class Solution {
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        sort(candidates.begin(),candidates.end());
        dfs(candidates,-1,0,target);
        for ( auto it1 = s.begin(); it1!= s.end(); it1++){
            v.push_back(*it1);
        }    
        return v;
    }
private:
    vector<vector<int>>v;
    set<vector<int>>s;
    vector<int>r;
    void dfs(vector<int> vv,int index,int sum,int target){
        if(sum>target) return;
        if(sum==target) {s.insert(r);return;}
        for(int i=index+1;i<vv.size();i++){
            r.push_back(vv[i]);
            dfs(vv,i,sum+vv[i],target);
            r.pop_back();
        }
    }
    
};