LeetCode 40. Combination Sum II

https://leetcode-cn.com/problems/combination-sum-ii/solution/hui-su-suan-fa-jian-zhi-python-dai-ma-java-dai-m-3/

class Solution {
    public List> combinationSum2(int[] candidates, int target) {
        List> res = new ArrayList<>();
        Arrays.sort(candidates);
        backtrack(candidates, target, 0, new ArrayList<>(), res);
        return res;
    }
    private void backtrack(int[] candidates, int remain, int start, List path, List> res){
        if(remain == 0){
            res.add(new ArrayList<>(path));
            return;
        }
        for(int i = start; i < candidates.length; i++){
            // Big Pruning
            if(candidates[i] > remain){
                break;
            }
            // Small Pruning
            if(i > start && candidates[i] == candidates[i - 1]){
                continue;
            }
            path.add(candidates[i]);
            backtrack(candidates, remain - candidates[i], i + 1, path, res);
            path.remove(path.size() - 1);
        }
    }
}