Computer Science - Problem Solving

Computer Science - Problem Solving

1. Algorithms

   • What is an algorithm?
     • A sequence of steps or instructions that are carried out to solve a problem or perform a task
     • What makes a successful algorithm?
       • Accuracy
         • It must lead to the expected outcome
       • Consistency
         • It must produce the same result each time it is run
       • Efficiency
         • It must solve the problem is the shortest possibile time
   • Different ways of representing an algorithm
     • Flowchart
       • A flowchart is a diagram that we can create to plan the flow of data in a solution
     • Written description
       • Simplest way of expressing an algorithm in words almost like a step by step instruction
     • Pseudocode
       • A way of designing a program in programming type statements that are not specific to any programming language
   • What are arithmetic operators?
     • Used to perform calculations such as addition
     • Examples
       • + Adding Values
       • - Subtracting Values

2. Variables and Constanats

   • What are variables?
     • A value that can change, depending on conditions or on information passed to the program
   • What are constants?
     • A value that cannot be altered by the program during normal execution

3. Programming Constructs

   • Selection
     • A decision within a computer program when the program decides to move on based on the results of an event
     • Decision or question
     • Selection allows there to be more than one path through a program
     • Selection is implemented in programming using IF statements
       • Programs consist of set instruction that is carried out one after another and there may be one or more paths
   • Iteration
     • In computer programming, this is a single pass through a set of instructions

4. Decomposition and Abstraction

   • What is abstraction?
     • Taking away detail that is not important so that we can focus on detail
   • What is decomposition?
     • Breaking down a problem into a smaller problem so that each one can be solved individually

5. Sorting Algorithms

   • Bubble Sort
     • Starts at the beggining of a list and first of all cheks the first item against the second item
   • Merge Sort
     • Works by dividing a list in half repeatedly until it has a set of lists that have one item in them and merges back
     • Divide and Conquer

6. Searching Algorithms

   • Linear Search
     • Move through a sequence till item is found
   • Binary search
     • Works by dividing a list in half and looking at the item in the middle