3sum.java

Leetoce 3 Sum Problem (Arrays)

class Solution {
    public List<List<Integer>> threeSum(int[] nums) {
        
    List<List<Integer>> result = new ArrayList<>();

    Arrays.sort(nums);

    for(int i=0;i<nums.length-2;i++)
    {
       //skip duplicates
       if(i>0 && nums[i]==nums[i-1])
       {
        continue;
       }

       int left = i+1;
       int right = nums.length-1;


       while(left<right)
       {
          int sum = nums[i] + nums[left] + nums[right];

          if(sum==0)
          {
            result.add(Arrays.asList(nums[i],nums[left],nums[right]));

            while(left<right && nums[left]==nums[left+1])
            {
                left++;
            }
         
           while(left<right && nums[right]==nums[right-1])
           {
            right--;
           }

           left++;
           right--;


          }

          else if(sum<0)
          {
            left++;
          }

          else{
            right--;
          }



       }






    }
  return result;


    }
}