Leetcode 15 3Sum

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.

Note: The solution set must not contain duplicate triplets.

For example, given array S = [-1, 0, 1, 2, -1, -4],A solution set is:[  [-1, 0, 1],  [-1, -1, 2]]

要怎么解决重复是一个问题

万能的sort就起作用了

public class Solution {    public List<List<Integer>> threeSum(int[] nums) {    List<List<Integer>> result = new ArrayList<>();    Arrays.sort(nums);    for (int i = 0; i + 2 < nums.length; i++) {        if (i > 0 && nums[i] == nums[i - 1]) {            continue;        }        int j = i + 1, k = nums.length - 1;                 while (j < k) {            if (nums[j] + nums[k] + nums[i] == 0) {                result.add(Arrays.asList(nums[i], nums[j], nums[k]));                j++;                k--;                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--;            } else {                j++;            }        }    }    return result;}}