6. Double pointer -- the sum of the two numbers of the incremental array is equal to the target number

 public int[] twoSum(int[] nums, int target) {
        int low = 0, high = nums.length-1;
        while(low < high){
           int sum = nums[low] + nums[high];
           if(sum < target) low++;
           else if(sum >target) high--;
           else  return new int[] { nums[low], nums[high]};
        }
        return new int[0];
    }

Running results ：