Algorithms

Algorithms

1. Sorting

   • Selection with interchange
     • Select the smallest number and swap with the first position
       • Excluding the first number which is already in the correct position, repeat step 1
         • Repeat excluding correctly positioned numbers until list is sorted
   • Bubble sort
     • Compare the first two numbers and place the smallest in the first position
       • Compare the second and third and place the smallest in the second position
         • Carry on up the list
           • Repeat until the list is sorted
   • Shuttle sort
     • Compare the first two numbers and swap if necassary
       • Compare the second and third and swap if necessary then compare the first and second
         • Repeat starting with the third and forth and carry on until the list is sorted
   • Quick sort
     • Select the first number as the pivot
       • Form two sublists with the first containing number less that or equal to the pivot and the second containing numbers greater than the pivot
         • Repeat the process on the sublists until every number has been a pivot or is in a list on its own

2. Searching

   • Linear search
     • Check each item in turn to see if it satisfies the criteria
   • Indexed sequential search
     • Data is ordered and subdivided
       • The first or last piece of data from each sublist is put in an index list
         • To find a piece of data the sublist is looked at then a linear search completed on the given sublist
   • Binary search
     • Look at the middle item
       • If this is the required item then the search is finished if not then decide whether the item is in the top or bottom half
         • Repeat

3. Communicating algorithms

   • Written english
   • Pseudo code
   • Programming languages
   • Flowcharts