题目
Given a set of candidate numbers (C) (without duplicates) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.
The same repeated number may be chosen from C unlimited number of times.
Note:
All numbers (including target) will be positive integers.
The solution set must not contain duplicate combinations.
For example, given candidate set [2, 3, 6, 7] and target 7,
A solution set is:
[
[7],
[2, 2, 3]
]
频度： 3
解题之法
class Solution {
public:
vector<vector<int> > combinationSum(vector<int> &candidates, int target) {
vector<vector<int> > res;
vector<int> out;
sort(candidates.begin(), candidates.end());
combinationSumDFS(candidates, target, 0, out, res);
return res;
}
void combinationSumDFS(vector<int> &candidates, int target, int start, vector<int> &out, vector<vector<int> > &res) {
if (target < 0) return;
else if (target == 0) res.push_back(out);
else {
for (int i = start; i < candidates.size(); ++i) {
out.push_back(candidates[i]);
combinationSumDFS(candidates, target - candidates[i], i, out, res);
out.pop_back();
}
}
}
};
