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2 Basic Algorithm

An algorithm is a sequence of solving a problem or a sequence that is used when a process is performed on a computer. An algorithm should have as much processing efficiency as possible, and it should be easy to understand. This section explains how to write flowcharts that describe algorithms, and also explains typical algorithms.

2 - 1 Flowchart

Flowchart is a commonly used notational convention of algorithms. Its main advantage is that it is visually easy to understand because the processing sequence is represented as a combination of symbols.

2-1-1 Main Symbols

The following are the main symbols that are used in flowcharts.

Enlarge original visual

Original source text

Symbol 
Symbol name 
Meaning 
This represents various processes (e.g., substitution, 
Process 
calculation). 
This represents start/end of flowchart. In some cases, 
Terminal 
a name is added to the terminal symbol that indicates 
the start. 
Decision 
This branches the process according to conditions. 
This connects each symbol and represents execution 
Flowline 
order. 
This represents the start/end of the iterative process 
(i.e., loop). It can also be described in the form of 
Loop limit 
“Variable name: Initial value, Increment, Final 
value”. 
This calls a predefined process. (It runs a flowchart 
Predefined 
that starts with the terminal symbol of identical 
process 
names.) 
This represents input, output of data (it is also 
Input/Output 
substituted for a process symbol in some cases). 

Source visual description

Original Basic Algorithm source layout. Source labels: Symbol; Symbol name; Meaning; Process; This represents various processes (e.g., substitution,.

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[Structured chart]

Structured charts that are used for representing algorithms include PAD, NS chart, and so on.