: Hi all, i'm new to algorithms and to this forum but was wondering if
: anyone has an algorithm which uses a merge sort to sort three sorted
: sequences into one?
:
: Any help would be much appreciated. Thanks in advance

Here is a simplified algorithm to merge 3 sorted lists. It is not the merge sort, because that's a full sorting algorithm, not just a way to merge sorted lists.

outList MergeLists (inListArray) {

  // Loop until all lists are empty

  while (length inListArray > 0) {
    int small = 0;

    // First find smallest item in all the lists

    for (i = 0 ; i < length inListArray; i++) {
      if (inListArray[i][0] < inListArray[small][0])
        small = i;
    }

    // Then add that item into the result list and remove it from the source list

    move inListArray[small][0] to outList

    // Finally check if that list becomes empty

    if (length inListArray[small] = 0) {
      remove inListArray[small] from inListArray
    }
  }
}

This code runs in O(n) time, where n is the number of total items.