Question

You have two sorted lists of integers, L1 and L2. You know the lengths of each list, L1 has length N1 and L2 has length N2. (a) Design an efficient algorithm (only pseudocode) to output a sorted list L1 ∩ L2 (the intersection of L1 and L2). (b) If you know that N2 > N1. What is the running time complexity of your algorithm? Justify. Important Note: For this problem, you don’t need to submit any implementation in Java. Only the pseudocode of your algorithm is required.

Answer 1

a)
1. Create a NULL head node, where we will append our result nodes.
2. Traverse the two lists until one is fully traversed or both are traversed.
   a) Compare the elements such that if element in list 1 is greater than element in list 2, traverse in list 2.
   b) Compare the elements such that if element in list 2 is greater than element in list 1, traverse in list 1.
   c) If both are equal, insert the element at the end of the resultant list.
  
3. The remaining list(one of 2) can not be part of the result.

b) As intersection will conatin to a maximum of min(n1, n2), elements. Hence max complexity can be O(N1)