Three_Sum.java

import java.util.*;
class Three_Sum {
    public List<List<Integer>> threeSum(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        Arrays.sort(nums);
        int n = nums.length;
        for(int i =0 ; i<n-2; i++){
            int left = i+1;
            int right = n-1 ;
            if (i>0 && nums[i]== nums[i-1]){
                continue;
            }
            else{
                while(left<right){
                    if(nums[left]+nums[right]> -nums[i]){
                        right--;
                    }
                    else if(nums[left]+ nums[right]< -nums[i]){
                        left++ ;
                    }
                    else{
                        result.add(Arrays.asList(nums[i],nums[left],nums[right]));
                        left++;
                        right -- ;
                        while(left<right && nums[left]== nums[left-1]){
                            left ++;
                        }
                        while(left<right && nums[right]==nums[right+1]){
                            right--;
                        }
                    }
                }
            }
        }
        return result;
        
    }

   
}