Leetcode第39题：Combination Sum（java实现）

题目描述：

题目解答：

class Solution {
    public List<List<Integer>> combinationSum(int[] candidates, int target) {
        //首先对候选列表进行排序
        Arrays.sort(candidates);
        List<List<Integer>> outcome=new ArrayList<>();
        List<Integer> currentList=new ArrayList<>();
        //尝试了几次觉得还是需要用到递归
        searchSet(outcome,candidates,target,0,currentList);
        return outcome;
    }
    public void searchSet(List<List<Integer>> outcome,int[] candidates, int target,int currentIndex,List<Integer> currentList){
        if(target==0){
            outcome.add(new ArrayList<Integer>(currentList));
        }else if(target>0){
            for(int i=currentIndex;i<candidates.length&&target>=candidates[i];i++){
                currentList.add(candidates[i]); 
                int temp_target=target-candidates[i];
                searchSet(outcome,candidates,temp_target,i,currentList);
                //在上一步的基础上退一步
                currentList.remove(currentList.size()-1);
            }
        }
    }
}

运行结果：