highschool/Grade 10/Computer Science/ICS4U1/Sorting Methods/Insertion Sort.md

Inssertion sort

What is Insertion sort

• a sorting algorithm
• dividng an array into sroted and unsorted sections
• removes elements in idividually from un unosrted section of the list and inserts it into its correct position in a new sorted seqeuence

Algorithm

• Set a key for the sections after the 1st element
• repeat the following
  • select first unsorted element as the key
  • move sorted elements to the right to create space
  • shift unsorted elemnet into correct position
  • advance the key to the right by 1 element
• Tests first unsorted element (key) to last element of sorted section
• If key is larger, insertion sort leaves the element in place and hte next index’s element becomes the key
• Else it finds the correct position within the sorted list
  • Duplicate the larger element in to one ahead of its current index each time the key is tested
  • By looping this, it makes space and inserts the key into that correct position

Pseudo0code

for x = 1 : n
    key = list[x]
    y = x-1
    while y >= 0 && key < list[y]
        insert list[x] into the sorted sequence list[1 .. x-1]
        list[y+1] = list[y]
        y--
    list[y+1] = key