Combination sum

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. 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] ]

public class Solution { public List> combinationSum(int[] candidates, int target) { List> result = new ArrayList<>(); Arrays.sort(candidates); dfs(result, new ArrayList(), candidates, target, 0); return result; } private void dfs(List> res, List path, int[] cand, int tar, int cur) { if(tar == 0) { res.add(new ArrayList(path)); return; } else if(tar > 0) { for(int i = cur; i < cand.length; i++){ path.add(cand[i]); dfs(res, path, cand, tar - cand[i], i); path.remove(path.size() - 1); } } } }