Question

I’m trying to create a function that takes a linked list and searches through each node in the list. If the node has a matched int, i1, then exchange with i2. Finally return a linked list that is a copy of its substitution.

Iteratively, I think I could just create a copy of the list, iterate through each node, and then check and replace.

for(LN copy = list; copy != null; copy = copy.next;)
  if (copy.value == i1)
   copy.value == i2;
return copy;

The prototype is

public static LN copySwap (LN list, int i1, int i2);

I’m not sure how I could begin to implement this recursively.

Answer 1

Assuming the constructor for LN takes a value and the next node in the list, this should work:

public static LN copySwap (LN list, int i1, int i2) {
    if (list == null) {
        return null;
    }
    return new LN(list.value == i1 ? i2 : list.value, copySwap(list.next, i1, i2));
}