组合总和

class Solution {
    List<List<Integer>> res = new ArrayList<>();
    List<Integer> list = new LinkedList<>();
    public List<List<Integer>> combinationSum(int[] candidates, int target) {
        dfs(target,candidates,0,0);
        return res;
    }

    public void dfs(int target,int[] candidates,int cur,int start){
        if(cur > target ) return;
        if(cur == target){
            res.add(new ArrayList<>(list));
            return;
        }
        for(int i=start;i<candidates.length;i++){//从start开始
            list.add(candidates[i]);
            dfs(target,candidates,cur+candidates[i],i);//这里是i不是i+1
            list.remove(list.size()-1);
        }
    }
}

class Solution {
    List<List<Integer>> res = new ArrayList<>();
    List<Integer> list = new LinkedList<>();
    public List<List<Integer>> combinationSum2(int[] candidates, int target) {
        Arrays.sort(candidates);
        dfs(target,candidates,0,0);
        return res;
    }

    public void dfs(int target,int[] candidates,int cur,int start){
        if(cur > target) return;
        if(cur == target){
            res.add(new ArrayList(list));
            return;
        }
        for(int i=start;i<candidates.length;i++){//从start开始
           if(i!=start && candidates[i] == candidates[i-1]) continue;//去重
            list.add(candidates[i]);
            dfs(target,candidates,cur+candidates[i],i+1);//i+1不重复取
            list.remove(list.size()-1);
        }
    }


}