Unit 2.1 Algorithms

Unit 2.1 Algorithms

1. Key Word Bank

   • Sorting - Arranging the elements in a list or collection in increasing or decreaing order of a particular property.
   • Abstraction - Using symbols, variables etc. to represent a 'real world' problem in a computer program, and removing unnecessary elements
   • Decompostion - The breaking down of large problems into smaller, easier to solve ones which can be combined to make the full solution.
   • Algorithmic Thinking - Identifying the steps involved in solving a problem.

2. Binary Search

   • Put the list in order
   • Take the middle value
   • Is it the value you want?
   • ELIF it is larger take the list of values to the left.
   • ELIF it is smaller take the list of values to the right.
   • Repeat until you get the desired value.

3. Linear Search

   • Check the first value
   • If it is the wanted value then stop
   • ELIF, Check the next value
   • Repeat until all have been checked.

4. Bubble Sort

   • Take the first and second elements.
   • Compare Them.
   • If Element 1 > 2, Swap them.
   • ELSE, Do Nothing
   • Do this until you can go all the way through without making any changes.

5. Merging Lists

   • Repeat until merged.
   • Split all elements into individual lists
   • Compare the first element in both lists.
   • Put the smallest in a new list
   • Compare the next of 1 list with the second of the second list
   • Put the smallest in a new list.

6. Merge Sort

   • Split a list into individual lists, of one element each
   • Merge the lists in pairs putting the smallest first
   • Merge until it is all in order

7. Insertion Sort

   • Element 1 is a 'sorted' list
   • The rest are 'unsorted' list
   • Compare the unsorted element to each element in the sorted list
   • If it is smaller, put it in front of that element
   • ELIF it is larger, compare with next value
   • If there are no more elements to compare with, put it in the final position
   • Repeat until all elements are 'sorted'

8. Flowcharts

   • They are used to represent algorithms
   • Shows the data that is input and output
   • Shows the processes taking place
   • Shows the decisions and repetitions
   • Lines/Arrows show the flow of control
   • Set Shapes are used; Start/End is an oval, INPUT/OUTPUT is a parallelogram, Processes are rectangles, and Decisions are diamonds with Yes/No answers coming off on different branches