LeetCode——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.
• Elements in a combination (a₁, a₂, � , a_k) must be in non-descending order. (ie, a₁ ? a₂ ? � ? a_k).
• 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] 

» Solve this problem

偷懒了，就在Combination Sum的基础上稍微修改了一下。

class Solution {
public:
    vector > combinationSum2(vector &candidates, int target) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        sort(candidates.begin(), candidates.end());
        set > ans;
        vector record;
        searchAns(ans, record, candidates, target, 0);
        
        vector > temp;
        for (set >::iterator it = ans.begin(); it != ans.end(); it++) {
            temp.push_back(*it);
        }
        return temp;
    }
    
private:
    void searchAns(set > &ans, vector &record, vector &candidates, int target, int idx) {
        if (target == 0) {
            ans.insert(record);
            return;
        }
        if (idx == candidates.size() || candidates[idx] > target) {
            return;
        }
        for (int i = 1; i >= 0; i--) {
            record.push_back(candidates[idx]);            
        }
        for (int i = 1; i >= 0; i--) {
            record.pop_back();
            searchAns(ans, record, candidates, target - i * candidates[idx], idx + 1);
        }
    }
};