Internal Sorting File Sorting Part 2

Bubble Sort of an array Inefficient --- O ( N2 ) easy to code, hence unlikely to contain errors Algorithm for outerloop = 1 to N for innerloop = 0 to N-2 if ( item[innerloop] > item[innerloop+1] ) swap item[i] and item[i+1]

Selection Sort of an array Easy to code, less swapping than bubble, but still O ( N2 ) Splits the array into 2 lists: one sorted (which slowly grows) one unsorted (which slowly shrinks) Algorithm find the smallest item in unsorted list swap smallest with start of unsorted list sorted_size ++; and unsorted_size --;

animations and comparisons at Quick Sort of an array Very Fast --- O ( N log2 N ) A pain to program Algorithm recursively partition the array into sub-lists sort infile outfile …… it's magic !!! animations and comparisons at http://www.sorting-algorithms.com/

Sorting a Linked List Linked Lists are necessary when we don't know the size of the list Sorting Operations for both arrays and linked lists comparisons arrays - need multiple indexes LL - need multiple pointers swaps with big records, LL is easier: just move a few pointers

Insertion Sort of Linked List Oversimplified Algorithm: While not eof newptr = new record with data from file temp = head while (temp != NULL) if (newptr->key < temp->key) insert newptr before temp else temp = temp->next

Ordered Binary Tree Alternative to building Singly Linked List Inserting new node is much easier Traversal to find insertion is log2N So, inserting N items takes N * log2 N compares 40 20 60 10 30 70