LeetCode Java First 400 题解-015

最新推荐文章于 2019-11-20 13:08:55 发布

原创最新推荐文章于 2019-11-20 13:08:55 发布 · 310 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#LeetCode

刷题专栏收录该内容

34 篇文章

订阅专栏

3Sum Medium

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]]

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

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

    if (nums.length < 3) return result;

    Arrays.sort(nums);

    int i = 0;

    while (i < nums.length - 2) {

        if (nums[i] > 0) break;

        int j = i + 1;

        int k = nums.length - 1;

        while (j < k) {

            int sum = nums[i] + nums[j] + nums[k];

            if (sum == 0) result.add(Arrays.asList(nums[i], nums[j], nums[k]));

            if (sum <= 0) while (nums[j] == nums[++j] && j < k) ;

            if (sum >= 0) while (nums[k--] == nums[k] && j < k) ;

        }

        while (nums[i] == nums[++i] && i < nums.length - 2) ;

    }

    return result;

}