Three sum

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

        int i = 0;
        while (i < nums.length) {
          int l = i+1;
          int r = nums.length - 1;

          if (i>0 && nums[i] == nums[i-1]) {
            i++;
            continue;
          }

          while (l < r) {
            int sum = nums[i] + nums[l] + nums[r];
            if (sum == 0) {
              List<Integer> tmpList = new ArrayList<Integer>();
              tmpList.add(nums[i]);
              tmpList.add(nums[l]);
              tmpList.add(nums[r]);
              result.add(tmpList);
              while (l < r && nums[l] == nums[l+1]) l += 1;
              while (l < r && nums[r] == nums[r-1]) r -= 1;
              l += 1;
              r -= 1;
            }
            else if (sum < 0) l += 1;
            else r -= 1;
          }
          i++;
        }
        return result;
    }
}