leetcode 39 java dfs

Given a set of candidate numbers (C) (without duplicates) 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]]

对于输入candidates=[1,2] ，target=3，遍历的方向如图： 

AC代码

public class Solution {    public List<List<Integer>> combinationSum(int[] candidates, int target) {        List<Integer> path =new ArrayList<Integer>();List<List<Integer>> result=new ArrayList<>();Arrays.sort(candidates);dfs(candidates,0,0,target,path,result);return result;    }    private  void dfs(int[] a, int now, int sum, int target,List<Integer> path,List<List<Integer>> result) {// TODO Auto-generated method stubif(sum==target){result.add(new ArrayList<>(path));return ;}if(sum>target){return ;}for(int i=now;i<a.length;i++){if(sum+a[i]>target){break;}path.add(a[i]);System.out.println("dfs("+i+")");dfs(a,i,sum+a[i],target,path,result);path.remove(path.size()-1);}}}