3Sum

最新推荐文章于 2022-01-27 22:44:32 发布

Hu_Jessie

最新推荐文章于 2022-01-27 22:44:32 发布

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分类专栏： LeetCode 文章标签： leetcode-java

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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]
]

 List<List<Integer>> lists = new ArrayList<>();
        Arrays.sort(nums);
       for (int i = 0; i < nums.length - 2; i++){
           if(i > 0 && nums[i] == nums[i - 1]) {
               continue;
           }
           int sum = - nums[i];
           int j = i + 1;
           int k = nums.length - 1;
           while(j < k) {
               if(nums[j] + nums[k] == sum){
                   List<Integer> ll = new ArrayList<>();
                   ll.add(nums[i]);
                   ll.add(nums[j]);
                   ll.add(nums[k]);
                   lists.add(ll);

                   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] > sum) {
                   k--;
               }else{
                   j++;
               }
           }
       }
        return lists;