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Holistic Education II : Computational Thinking Holistic Education II : Computational Thinking

Algorithmic Thinking

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Algorithms

• Many of life’s essential activities involve following a sequence of simple and discrete steps to solve some large problem.

• Algorithm is a sequence of discrete actions that will result in achieving some goal or solving some problem.

Complex Process

Sequence of actions

input output

Algorithm

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Algorithms in daily life

Football Players: when execute a play on the field

Piano Players: when read and play a musical score

Actors: when read and execute a script for performance

Drivers: when follow to getting from one city to another

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(EX) Algorithm: a sequence of computational actions

INPUT OUTPUT

ACTION

ORDER

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The Properties of Algorithm

1. Be Meaningful(Semantics) refers to the meaning of the actions that occur in an algorithm

2. Be Unambiguous the action is not subject to conflicting interpretations

action must have only one possible interpretation

3. The Order be defined the directions describe an orderly sequence of discrete actions

4. Be Finite we can not reach the goal if we are required to follow a never-ending

sequence of actions

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Software and Programming Languages

A computer is able to perform simple actions such as adding two integer numbers

Computer software(program) provides the instructions for telling a computer the algorithm (actions) that it should follow to achieve some goal

How to express the algorithm in computer? We need the Programming Language

A programming language is a language that is designed to precisely and compactly express computational algorithm

The computer can understand what they have to act There are many types of language

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Actions

Since any executable algorithm must be expressed as a sequence of possible actions, we must first understand what actions a computer might possible take

The ways of expressing algorithms and computational processes Name Binding Selection Repetition Modularization

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Name Binding (proper naming & state)

Name binding is the association of a name with a value Ex) X 3 Y 4 Z 3 + 4

Proper naming enables a computer scientist to more clearly reason about the algorithm and data of the program

Ex) DollarsPerGallon 3.75 TankCapacity 10

DollarsToFill TankCapacity * DollarsPerGallon

The computational state of a program is the collection of name bindings that are active at any single point in time

Fahrenheit

State.value

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Selection (one-way)

Control flow statements are commands that control the specific ordering of the actions performed by a computer program

One-way selection: Perform an action or skip the action

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Selection (two-way)

Two-way selection

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Selection (multiway)

Multiway selection : use elseif instead of else to cascade two-way selections

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Repetition

Computers must also execute a sequence of actions repeatedly in order to achieve some greater outcome

A loop is a control structure that repeatedly executes a sequence of actions

While loop

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Modularization

Modularization is a vital element of programming that allows us to define new computable actions by assigning a name to some computable process

Algorithms can be modularized by breaking them into independent sub-processes

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Modularization: Well-designed modules

Well-designed modules should meet several criteria Understandability Encapsulation Composition

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Modularization : Modularity

Modularity is an extremely powerful technique for designing complex algorithms

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Modularization : Module Flexibility

Modules are made flexible by allowing users to feed input values into the code

Inputs: “parameters”

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(EX) Modularization : Module Flexibility

Optimize the flexibility of grillSteak module

grillSteak(65, 130, 2) The steak to be grilled from a starting point of 65 degrees until it reaches a

temperature of at least 130 degree where the temperature increases by 2 degree for every three minutes of grill time

grillSteak(94, 155, 13) The steak to be grilled from a starting point of 94 degrees until it reaches a

temperature of at least 155 degree where the temperature increases by 13 degree for every three minutes of grill time

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Algorithmic Thinking ?