LeetCode | Combination Sum II

题目：

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.
• Elements in a combination (a1, a2, … , ak) must be in non-descending order. (ie, a1 ≤ a2 ≤ … ≤ ak).
• 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] 

思路：

常规递归问题。

代码：

class Solution {public:    vector<vector<int> > result;    vector<int> v;    vector<int> candidates;    vector<vector<int> > combinationSum2(vector<int> &num, int target) {        this->candidates = num;        sort(this->candidates.begin(),this->candidates.end());        getCombination(0,0,target);        return result;    }        void getCombination(int k, int sum, int target)    {        if(sum==target)        {            for(int k=0;k<result.size();k++)            {                if(result[k]==v)                {                    return;                }            }            result.push_back(v);        }        else if(sum>target)        {            return;        }        else if(k>=candidates.size())        {            return;        }        else        {            getCombination(k+1, sum, target);            v.push_back(candidates[k]);            getCombination(k+1, sum+candidates[k], target);            v.pop_back();        }    }};