ringkasan alpro: Counting

Counting

Algorithm Development

Counting mechanisms are very frequently used in computer algorithms. Generally a count must be made of the number of items in a set which possess some particular property or which satisfy some particular condition or conditions. This class of problem is typified by the “examination marks” problem.

As a starting point for developing a computer algorithm for this problem we can consider how we might solve a particular example by hand.

Suppose thar we are given the set of marks.

55, 42, 77, 63, 29, 57, 89

To make a count of the passes for this set we can start at the left, examine the first mark (i.e. 55), see if it is ≥50, and remember that one student has passed so far. The second mark is then examined and no adjustment is made to the count. When we arrive at  the third mark we see it is ≥50 and so we add one to our previous count. The process continues in a similiar manner until all marks has been tested.

In more detail we have:

Algorithm Description

1.    Prompt and then read the number of marks to be processed

2.   Initiaize count to zero

3.   While there are still marks to be processed repeatedly do

(a)Read next marks,

(b)        If it a pass (i.e. ≥50) then add one to count

4.   Write out total of passes

Pascal Implementation

Notes on design

1.    Initially, and each time through the loop, the variable count represents the number of passes so far en countered.

2.   It was possible to use subtitution to improve on the original solution to the problem.

3.   An end-of-line test is included to handle multiple lines of data.

Applications

All forms of counting.