package array;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.LinkedList;

import java.util.List;

/**

* Created by qiaoying on 2018/7/22.

*/

public class ThreeSum {

public static List<List<Integer>> threeSum(int[] nums) {

List<List<Integer>> result = new LinkedList<List<Integer>>();

if (nums != null && nums.length > 2){

Arrays.sort(nums);

for (int i = 0; i < nums.length - 2; ){

int j = i + 1;

int k = nums.length - 1;

while (j < k){

if (nums[j] + nums[k] == -nums[i]){

List<Integer> list = new ArrayList<Integer>(3);

list.add(nums[i]);

list.add(nums[j]);

list.add(nums[k]);

result.add(list);

k--;

j++;

while (j < k && nums[j] == nums[j - 1]){

j++;

}

while (j < k && nums[k] == nums[k + 1]){

k--;

}

}else if (nums[j] + nums[k] > -nums[i]){

k--;

while (j < k && nums[k] == nums[k + 1]){

k--;

}

}else {

j++;

while (j < k && nums[j] == nums[j - 1]){

j++;

}

}

}

i++;

while (i < nums.length - 2 && nums[i] == nums[i -1]){

i++;

}

}

}

return result;

}

public static void main(String[] args){

int[] a = {-1,0,1,2,-1,-4};

List<List<Integer>> b = threeSum(a);

System.out.println(b.size());

}

}