# 39. Combination Sum
Given a set of candidate numbers (candidates) (without duplicates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.
The same repeated number may be chosen from candidates unlimited number of times.
Note:
- All numbers (including target) will be positive integers.
- The solution set must not contain duplicate combinations. Example 1:
Input: candidates = [2,3,6,7], target = 7,
A solution set is:
[
[7],
[2,2,3]
]
Example 2:
Input: candidates = [2,3,5], target = 8,
A solution set is:
[
[2,2,2,2],
[2,3,3],
[3,5]
]
# Solution
Approach 1: DFS.
# Code (Python)
Approach 1:
# Code (C++)
Approach 1:
class Solution {
private:
vector<vector<int>> solutionSet;
void combinationSum(vector<int>& candidates, int head, int target, vector<int>& solution) {
if (target == 0)
{
solutionSet.push_back(solution);
return;
}
for (int i = head; i < candidates.size(); ++i)
{
if (candidates[i] > target)
break;
solution.push_back(candidates[i]);
combinationSum(candidates, i, target - candidates[i], solution);
solution.pop_back();
}
}
public:
vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
vector<int> solution;
std::sort(candidates.begin(), candidates.end());
combinationSum(candidates, 0, target, solution);
return solutionSet;
}
};