LeetCode 40 Combination Sum II（数组中求和等于target的所有组合）

package leetcode_50;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/***
 * 
 * @author pengfei_zheng
 * 数组中求和等于target的所有组合
 */
public class Solution40 {
    public List<List<Integer>> combinationSum2(int[] nums, int target) {
        List<List<Integer>> list = new ArrayList<>();
        Arrays.sort(nums);
        backtrack(list, new ArrayList<>(), nums, target, 0);
        return list;
        
    }

    private void backtrack(List<List<Integer>> list, List<Integer> tempList, int [] nums, int remain, int start){
        if(remain < 0) return;
        else if(remain == 0) list.add(new ArrayList<>(tempList));
        else{
            for(int i = start; i < nums.length; i++){
                if(i > start && nums[i] == nums[i-1]) continue; // skip duplicates
                tempList.add(nums[i]);
                backtrack(list, tempList, nums, remain - nums[i], i + 1);
                tempList.remove(tempList.size() - 1); 
            }
        }
    } 
}