https://leetcode.com/problems/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]
]
代码：
class Solution {
public:
vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
int n = candidates.size();
vector<int> out;
vector<vector<int> > ans;
dfs(candidates, target, 0, ans, out);
return ans;
}
void dfs(vector<int> &candidates, int target, int st, vector<vector<int>> &ans, vector<int> &out) {
if(target < 0) return ;
else if(target == 0) {ans.push_back(out); return ;}
for(int i = st; i < candidates.size(); i ++) {
out.push_back(candidates[i]);
dfs(candidates, target - candidates[i], i, ans, out);
out.pop_back();
}
}
};