Question
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
DFS
Code
class Solution {
public List<List<Integer>> combinationSum(int[] candidates, int target) {
Arrays.sort(candidates);
List<List<Integer>> results = new ArrayList<>();
List<Integer> res = new ArrayList<>();
dfs(candidates, 0, target, results, res);
return results;
}
public void dfs(int[] candidates, int start, int target, List<List<Integer>> results, List<Integer> res) {
if(target < 0) return;
if(target == 0) {
results.add(new ArrayList<Integer>(res));
return;
}
for(int i=start; i<candidates.length; i++) {
res.add(candidates[i]);
dfs(candidates, i, target-candidates[i], results, res);
res.remove(res.size()-1);
}
}
}