40. Combination Sum II(C++)

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]
]

Solution:  //回溯，注意与上一个区分

class Solution {
public:

    void combination(vector<int>& candidates,int target,vector<int>& tmp,vector<vector<int>>& myvec,int start){
        if(!target){
            myvec.push_back(tmp);
            return;
        }
        for(int i=start;i<candidates.size()&&candidates[i]<=target;i++){
            tmp.push_back(candidates[i]);
            combination(candidates,target-candidates[i],tmp,myvec,i+1);
            tmp.pop_back();
            while(candidates[i]==candidates[i+1]) i++;
        }
    }
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        vector<vector<int>> myvec;
        vector<int> tmp;
        sort(candidates.begin(),candidates.end());
        combination(candidates,target,tmp,myvec,0);
        return myvec;
    }
};