[LeetCode] Combination Sum

Total Accepted: 9767 Total Submissions: 37455

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, … , a_k) must be in non-descending order. (ie, a₁ ≤ a₂ ≤ … ≤ a_k).
• 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 ArrayList<ArrayList<Integer>> combinationSum(int[] candidates, int target) {        ArrayList<ArrayList<Integer>>   list = new ArrayList<ArrayList<Integer>>();        ArrayList<Integer>              path = new ArrayList<Integer>();                Arrays.sort(candidates);        dfs(candidates, list, path, target, 0);                return list;    }        public void dfs(int[] candidates, ArrayList<ArrayList<Integer>> list, ArrayList<Integer> path, int target, int end) {        if (target == 0) {            list.add(new ArrayList<Integer>(path));            return;        }        for (int i = end; i < candidates.length; i++) {            if (candidates[i] > target) continue;             path.add(candidates[i]);            dfs(candidates, list, path, target - candidates[i], i > end ? i : end);            path.remove(path.size() - 1);        }    }}