三数之和-暴力破解法

代码实现

/*
 * 三数之和问题
 * */
public class ViolenceThreeSum {
    public static List<List<Integer>> ThreeSum(int nums[]){
        //使用三重for循环解决三数之和问题
        List<List<Integer>> lists = new ArrayList<>();
        for (int i = 0; i < nums.length - 2; i++) {
            for (int j = i + 1; j < nums.length - 1; j++) {
                for (int k = j + 1; k < nums.length; k++) {
                    if(nums[i] + nums[j] + nums[k] == 0){
                        List<Integer> list = new ArrayList<>();
                        list.add(nums[i]);
                        list.add(nums[j]);
                        list.add(nums[k]);
                        lists.add(list);
                    }
                }
            }
        }
        //排序
        for (int i = 0; i < lists.size(); i++) {
            Collections.sort(lists.get(i));
        }
        //去重
        Set<List<Integer>> set = new HashSet<>();
        set.addAll(lists);
        lists.clear();
        lists.addAll(set);
        return lists;
    }

    public static void main(String[] args) {
        int[] nums = {-1,0,1,2,-1,-4};
        List<List<Integer>> lists = ViolenceThreeSum.ThreeSum(nums);
        System.out.println(Arrays.toString(lists.toArray()));
    }
}