15.三数之和.cpp

/*
 * @lc app=leetcode.cn id=15 lang=cpp
 *
 * [15] 三数之和
 */

// @lc code=start
class Solution
{
public:
    vector<vector<int>> threeSum(vector<int> &nums)
    {
        vector<vector<int>> result;
        sort(nums.begin(), nums.end());
        for (int i = 0; i < nums.size(); i++)
        {
            if (nums[i] > 0)
            {
                return result;
            }
            if (i > 0 && nums[i] == nums[i - 1])
            {
                continue;
            }
            int left = i + 1;
            int right = nums.size() - 1;
            while (right > left)
            {
                if (nums[i] + nums[left] + nums[right] > 0)
                {
                    right--;
                }
                else if (nums[i] + nums[left] + nums[right] < 0)
                {
                    left++;
                }
                else
                {
                    result.push_back(vector<int>{nums[i], nums[left], nums[right]});

                    left++;
                    while (right > left && nums[left] == nums[left - 1])
                        left++;
                    right--;
                    while (right > left && nums[right] == nums[right + 1])
                        right--;
                }
            }
        }
        return result;
    }
};
// @lc code=end