CS paper 1

• Decomposition - breaking complex problems into smaller problems and solving each individually.
• Abstraction - picking out important features of a problem and ignoring the rest.
• Pseudocode - quicker to write, easy to convert.
• flowcharts

  A) start/end

  B) connects shapes

  C) input/output

  D) process

  E) decision

  
• Binary search - finds middle continuously. Requires the list to be ordered.
• Linear search - checks each item of the list. Can be unordered. Takes longer on large lists.
• Bubble sort - swaps elements in list. Simple, takes a long time.
• Merge sort - splits list and pairs together. Faster on large lists, uses more memory.
• Integer - whole number only

  Float - number w decimal point

  Boolean - two values (true/false)

  Character - single letter, number, symbol

  String - represent text
• Selection - order steps carried out in. IF, THEN, ELSE.
• Iteration - number of times repeated until condition met. WHILE, REPEAT - UNTIL, FOR.
• Subroutines - sets of instructions stored under one name. Will always return a value.
• Local variable - only used in structure declared in.

  Global variable - used any time after declaration.
• One dimensional arrays - stored in a single row, a list.

  Two dimensional arrays - stored in a table structure, rows and columns.
• len(string) - return number of characters in string.
• string.index(substring) - returns the index/position of the first occurrence of substring in the string.
• string[x] - extracts character at position x in string.
• string[x:y] - extracts position of x and positions up to but not including y.
• string.upper() - returns string in uppercase.
• string.lower() - returns string in lowercase.
• string.isdigit() - returns true if string contains only digits and false otherwise.