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] ]
class Solution { public: vector<vector<int>> combinationSum2(vector<int>& candidates, int target) { sort(candidates.begin(), candidates.end()); vector<vector<int>> res; vector<int> combination; combinationSum2(candidates, target, res, combination, 0); return res; } private: void combinationSum2(vector<int>& candidates, int target, vector<vector<int>>& res, vector<int>& combination, int begin){ if(!target){ res.push_back(combination); return; } for(int i = begin; i < candidates.size() && target >= candidates[i]; ++i){ if(i > begin && candidates[i] == candidates[i-1]) continue; //关键在于是递归进去的还是 i自加进去,后者要去除 combination.push_back(candidates[i]); combinationSum2(candidates, target-candidates[i], res, combination, i+1); combination.pop_back(); } } };