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WJEC CG3.5 & 3.7
Topics 5 & 7: Algorithms and Logical Operations
Question | Answer |
---|---|
Insertion sort | Items are copied one by one from the input (array) to the output (array); Each new item is inserted in the correct place in the output. |
Bubble sort | A pass is made through the data, comparing each value with the following one and swapping them if necessary. A number of passes is made until the data is in order. |
Defining algorithms | Structured English; flowcharts; pseudo-code. |
ByValue | local copy of the data is created for the procedure (discarded later) |
ByReference | the address of the required data is passed to the procedure (rather than the actual value of the data) |
Recursive Algorithm | A recursive algorithm is one which calls itself. It must also have a “base case” to allow it to terminate. Example: Binary search; Quicksort; Traversing binary tree; Factorial calculation; Towers of Hanoi; Fibonacci calculation. |
Standard Module | is one which carries out a standard task. It is pre-written / pre-tested and may be supplied with the language. The benefits include the fact that the standard module has already been written, which saves time and effort. It has also been tested. |
Quicksort (description) | An item/pivot selected (which item is unimportant) Condone “middle”; Produce two new lists of smaller and larger numbers; Repeat above points on new sub lists (recursively) until sorted. |