LeetCode 40 - Combination Sum II

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,
… , 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]

 

My Code

class Solution {
public:
void doCombinationSum(vector<vector<int> >& sets, vector<int>& set, vector<int>& candidates, int target, int idx)
{
if (0 == target)
{
sets.push_back(set);
return;
}

for (int i = idx; i < candidates.size() && candidates[i] <= target;)
{
set.push_back(candidates[i]);
doCombinationSum(sets, set, candidates, target - candidates[i], i + 1);
set.pop_back();
i++;
while (i < candidates.size() && candidates[i-1] == candidates[i])
i++;
}
}

vector<vector<int> > combinationSum2(vector<int>& candidates, int target) {
vector<int> set;
vector<vector<int> > sets;
sort(candidates.begin(), candidates.end());

doCombinationSum(sets, set, candidates, target, 0);

return sets;
}
};

Runtime: 8 ms