Untitled

import java.util.*;

public class ThreeSum {
    public static List<List<Integer>> threeSum(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        Arrays.sort(nums); // Step 1: Sort the array
        
        for (int i = 0; i < nums.length - 2; i++) {
            // Avoid duplicates for the fixed number
            if (i > 0 && nums[i] == nums[i - 1]) continue;
            
            int target = -nums[i];
            int left = i + 1, right = nums.length - 1;

            while (left < right) {
                int sum = nums[left] + nums[right];
                if (sum == target) {
                    result.add(Arrays.asList(nums[i], nums[left], nums[right]));
                    left++;
                    right--;
                    
                    // Skip duplicates for the left and right pointers
                    while (left < right && nums[left] == nums[left - 1]) left++;
                    while (left < right && nums[right] == nums[right + 1]) right--;
                } else if (sum < target) {
                    left++;
                } else {
                    right--;
                }
            }
        }
        return result;
    }

    public static void main(String[] args) {
        int[] nums = {-1, 0, 1, 2, -1, -4};
        System.out.println(threeSum(nums));
    }
}