Merge 2 Sorted Linked List in c++ Algorithm

 

Here is an algorithm for merging two sorted linked lists in C++:

1. Create a new dummy node for the merged list.
2. Initialize a pointer, curr, to point to the dummy node.
3. Iterate through each element in both lists using two pointers, l1 and l2.
4. Compare the first elements of each list.
5. If the element in list 1 is smaller, append it to the merged list and move the pointer for list 1 to the next element.
6. If the element in list 2 is smaller, append it to the merged list and move the pointer for list 2 to the next element.
7. Repeat steps 4-6 until one of the lists is exhausted.
8. Append the remaining elements from the non-empty list to the merged list.
9. Return the dummy node's next pointer, as it is the head of the merged list.

Alternatively, for recursive algorithm:

1. Create a helper function for merging two sorted linked lists.
2. In the helper function, check for the base case: if one of the lists is empty, return the remaining list.
3. Compare the first elements of each list.
4. If the element in list 1 is smaller, append it to the merged list and recursively call the helper function with the next element of list 1 and the entire list 2.
5. If the element in list 2 is smaller, append it to the merged list and recursively call the helper function with the entire list 1 and the next element of list 2.
6. Repeat steps 3-5 until the base case is reached.
7. Return the head of the merged list.

Both of these algorithms will effectively merge two sorted linked lists in C++, with the iterative algorithm having a faster time complexity of O(n) and the recursive algorithm having a time complexity of O(n log n).