# 39 Combination Sum – Medium

### Problem:

Given a set of candidate numbers (C) 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. 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 2,3,6,7 and target 7, A solution set is: [7] [2, 2, 3]

### Thoughts:

Idea is to use a modified DFS.

### Solutions:

``````public class Solution {
public List<List<Integer>> combinationSum(int[] candidates, int target) {
List<List<Integer>> result = new ArrayList<List<Integer>>();
if(candidates == null || candidates.length == 0) return result;
ArrayList<Integer> current = new ArrayList<Integer>();
Arrays.sort(candidates);
combinationSum(candidates, target, 0, current, result);
return result;
}
public void combinationSum(int[] candidates, int target, int j, ArrayList<Integer> curr, List<List<Integer>> result){
if(target == 0){
ArrayList<Integer> temp = new ArrayList<Integer>(curr);
return;
}
for(int i=j; i<candidates.length; i++){
if(target < candidates[i])
return;