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Algorithm Executors

Algorithm Executors

Slide 6

From the list of tasks given, select those that are clearly formulated.

• Go there, I don’t know where. Bring something, I don’t know what.
• Count the stars in the sky.

Slide 7

Algorithm properties

• Efficiency
• Discreteness (step by step)
• Determinism
• (certainty)
• Understandability
• Feasibility
• Mass character

Slide 8

• Productivity.
• Discreteness (step by step)

Slide 9

• Determinism (certainty).
• Clarity.
• Feasibility.
• Mass character

Slide 10

Algorithm recording forms

Verbal and formulaic.

• 1 step 23+34=57
• Step 2 57*57=3249
• Step 3 3249/3=1083

Using an algorithmic language.

Expression.

• argy,z:int
• resx:int
• x:=2*y
• x:=x+z

Flowcharts.

Slide 11

Flowchart elements

1. Start
2. Data
3. Command Sequence
4. Condition
5. Declaring Variables

Slide 12

Types of Algorithms

• Linear
• Branched (algorithmic structures “branching” and “selection”)
• Cyclic (algorithmic structure “cycle”)
• Auxiliary

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• A linear algorithm is an algorithm in which instructions are executed sequentially, one after another.
• A branched algorithm is an algorithm in which, depending on the truth or falsity of a condition, one or another series of commands will be executed.
• A cyclic algorithm is an algorithm in which the same sequence of actions is performed repeatedly (or not once) until a condition is met.
• An auxiliary algorithm is an independent algorithm equipped with a header that allows this algorithm to be called from other algorithms.

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Linear algorithm

Example. Tree planting algorithm

1. Start
2. End
3. Dig a hole in the ground
4. Place the seedling in the hole
5. Bury the hole with the seedling with soil
6. Water the seedling with water

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Branched algorithm

Example: Of three coins of the same value, one is counterfeit (light). How to find it using one weighing on a cup scale without weights?

Slide 16

Round robin algorithm

Math homework.

Slide 17

Let's repeat...

4. List the main elements of a flowchart and their purpose.

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Practical work

Think over and create on a computer using a graphical vector editor block diagrams of linear, branched, cyclic algorithms.

Explanation: When working, use the elements of a flowchart.

Slide 19

Homework

• A creative message on the topic: "Algorithms around us", using reasonable sources (optional).

A creative message will definitely be appreciated!

Slide 20

When creating the presentation, the teaching materials of N. D. Ugrinovich and L. L. Bosovoy were used.

View all slides

Abstract

Lesson topic

Target

Tasks:

Lesson type: A lesson in learning new knowledge.

Equipment

2. Multimedia projector.

Equipment:

Power point presentation.

Duration: two lessons of 45 minutes.

Progress of the lesson

1.Organizational moment

Teacher

Teacher

Teacher: Well done boys!

Student.

Speech example . The word “algorithm” comes from the name of the Arab scientist Muhammad ibn Musa al-Khwarizmi. Al-Khorezmi lived and worked in the 9th century; he formulated the rules for performing arithmetic operations in the decimal positional number system.

Teacher: So, ah algorithm is a description of a deterministic sequence of actions aimed at obtaining a result from the initial data in a finite number of discrete steps using commands understandable to the performer.

What algorithms do you know, and who or what is executing the algorithms?

Exchange of opinions in groups.

Teacher

Count the number of windows in your house.

Count the stars in the sky.

Give a detailed description of the road from the door of your house to school (on foot, by bus or other transport).

Go there, I don’t know where.

Bring something, I don’t know what.

Teacher:

Productivity. Obtaining the required result in a finite number of steps; this means that an incorrect algorithm that does not achieve the goal does not need to be considered an algorithm at all.

Discreteness (step by step). By discreteness we mean that the algorithm consists of a sequence of actions, steps. It is impossible to complete each next step without completing the previous ones. The last step, as a rule, produces the result of the algorithm.

Means that the actions performed at each step are uniquely and precisely defined.

Clarity. The algorithm must be understandable not only to the author, but also to the performer.

Feasibility. The algorithm must contain commands written in an understandable language and executable by the performer.

Mass character. The same algorithm can be used to solve a large number of similar problems with different conditions.

Teacher.

1.Verbal-formular

For example, Create an algorithm for solving the arithmetic expression (23+34)*57/3

1 step 23+34=57

Step 2 57*57=3249

Step 3 3249/3=1083

For example, Create an algorithm for solving the algebraic expression x=2y+z

alg Expression

args y,z:int

3. Tables

4. Block diagrams,

Teacher: ).

4. Stage of consolidation of knowledge.

4.1 .

Sample questions:

1. Give examples of algorithms known to you.

2. List the main properties of algorithms and illustrate them with examples.

3. What forms of description of algorithms do you know?

Teacher:

4.2. Individual work on the computer:

Teacher: Write down your homework:

1. Computer science and ICT: textbook for grade 9 / N. D. Ugrinovich, pp. 105-109 (required).

Command Sequence

Declaring Variables

Ermakova Veronika Vikentievna, computer science teacher, Municipal Budgetary Educational Institution Secondary School No. 19 of the city of Belovo

Methodological development of a lesson in computer science

for 9th grade students on the topic “Algorithm. Properties of the algorithm. Block diagrams"

Lesson topic: Algorithm. Properties of the algorithm. Flowcharts.

Target: Familiarization of students with the concept of an algorithm, its properties, algorithm executor and basic algorithmic structures.

Tasks:

1. Give the concept of an algorithm, an algorithm executor and consider the properties of algorithms.

2. Introduce students to basic algorithmic structures.

3. Teach students to create flowcharts of algorithms.

4. Promote the development of students’ information culture and logical thinking.

Lesson type: A lesson in learning new knowledge.

Equipment: 1. Modern computers with Internet access.

2. Multimedia projector.

Equipment: Poster "Basic Algorithmic Structures".

Power point presentation.

List of used literature: UMK N. D. Ugrinovich, L. L. Bosovoy

Duration: two lessons of 45 minutes.

Progress of the lesson

1.Organizational moment

Teacher: Good afternoon guys! Today, we will begin to study the most interesting and important topic of the computer science course “ALGORITHM”. (Presentation demonstration, 1 slide)

2. The stage of preparing students for active conscious assimilation of knowledge.

Teacher: I suggest you independently find on the Internet the meaning of the word “ALGORITHM”.

Individual work of students on a PC, brief recording of the concept of an algorithm in a notebook, exchange of opinions.

Teacher: Well done boys! is a description of a deterministic sequence of actions aimed at obtaining a result from the initial data in a finite number of discrete steps using commands understandable to the performer. (Presentation demonstration, 2 slide)

My assistant, your classmate, prepared a historical background on the origin of the word “algorithm”; for this he used a textbook, reference books, and Internet resources.

Student. Historical reference. Origin of the word "ALGORITHM"

Speech example . The word “algorithm” comes from the name of the Arab scientist Muhammad ibn Musa al-Khwarizmi. Al-Khorezmi lived and worked in the 9th century; he formulated the rules for performing arithmetic operations in the decimal positional number system.

In the Latin translation of Al-Khwarizmi’s book, the rules began with the words “Algorizmi said.” Over time, people forgot that “Algorism” is the author of the rules, and began to simply call the rules algorithms. Currently, the word “algorithm” is one of the most important concepts in computer science. (Presentation demonstration, 3 slide)

3. Stage of assimilation of new knowledge.

Teacher: So, ah algorithm is a description of a deterministic sequence of actions aimed at obtaining a result from the initial data in a finite number of discrete steps using commands understandable to the performer.

What algorithms do you know, and who or what is executing the algorithms?

How do you understand Norbert Wiener’s statement: “A machine is only worth as much as the man who works on it?” (Demonstration of presentation 4 slide)

Exchange of opinions in groups.

Teacher: Performer – a person, a group of people, an animal, a technical device capable of executing given commands. (Presentation demonstration 5 slide)

Any task can be successfully solved only when it is clearly described. From the list of tasks below, select those that are clearly formulated:

Count the number of windows in your house.

Count the stars in the sky.

Give a detailed description of the road from the door of your house to school (on foot, by bus or other transport).

Go there, I don’t know where.

Bring something, I don’t know what.

(Presentation demonstration 6 slide)

Teacher: Let's consider the properties of the algorithms (teacher's story with elements of conversation).

Productivity. Obtaining the required result in a finite number of steps; this means that an incorrect algorithm that does not achieve the goal does not need to be considered an algorithm at all.

Discreteness (step by step). By discreteness we mean that the algorithm consists of a sequence of actions, steps. It is impossible to complete each next step without completing the previous ones. The last step, as a rule, produces the result of the algorithm.

Determinism (certainty). Means that the actions performed at each step are uniquely and precisely defined.

Clarity. The algorithm must be understandable not only to the author, but also to the performer.

Feasibility. The algorithm must contain commands written in an understandable language and executable by the performer.

Mass character. The same algorithm can be used to solve a large number of similar problems with different conditions.

(Demonstration of presentation 7, 8, 9 slides)

Teacher: Guys, here are the forms for recording algorithms (d demonstration of algorithm recording forms).

1.Verbal-formular

For example, Create an algorithm for solving the arithmetic expression (23+34)*57/3

1 step 23+34=57

Step 2 57*57=3249

Step 3 3249/3=1083

2. Using an algorithmic language

For example, Create an algorithm for solving the algebraic expression x=2y+z

alg Expression

args y,z:int

3. Tables

4. Block diagrams, in which geometric shapes are used to indicate the steps of the algorithm.

(Presentation demonstration, 10-11 slides)

Teacher: What types of algorithms are there? ( Teacher's story showing examples of various algorithmic structures).

Linear is an algorithm in which commands are executed sequentially one after another.

Branched (algorithmic structures “branching” and “selection”) - an algorithm in which, depending on the truth or falsity of the condition, one or another series of commands will be executed.

Cyclic (algorithmic structure “cycle”) is an algorithm in which the same sequence of actions is performed repeatedly (or not once) until a condition is met.

Auxiliary - an independent algorithm, equipped with a header that allows you to call this algorithm from other algorithms.

(Presentation demonstration, 12-16 slides)

4. Stage of consolidation of knowledge.

4.1 . Independent work in groups by cards. The group leader reports the results to the teacher.

Sample questions:

1. Give examples of algorithms known to you.

2. List the main properties of algorithms and illustrate them with examples.

3. What forms of description of algorithms do you know?

4. List the main elements of a flowchart and their purpose. (Presentation demonstration, slide 17)

Teacher: Information break (physical minute).

4.2. Individual work on the computer:

Creation on a computer using a graphical vector editor of a block diagram of linear, branched, cyclic algorithms. Explanation: When working, you must use the elements of a flowchart. (Presentation demonstration, slide 18)

5.Homework information stage.

Teacher: Write down your homework:

1. Computer science and ICT: textbook for grade 9 / N. D. Ugrinovich, pp. 105-109 (required).

2. If you wish, you can prepare a creative message on the topic: “Algorithms around us”, using reasonable sources. A creative message will definitely be appreciated!

(Presentation demonstration, slide 19).

Thank you for the lesson! Goodbye, guys.

Command Sequence

Declaring Variables

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Linear algorithm The simplest problems have a linear solution algorithm (they have a “following” structure). The linear structure algorithm is a sequence of actions and does not contain any conditions. Thus, in such algorithms all stages of solving a problem are performed strictly sequentially.

Cyclic algorithms A cycle is a repeated repetition of actions. Cyclic algorithms With post condition - In this loop, the condition is checked from the beginning, then the action occurs. With pre condition - Here the action occurs at the beginning, then the condition is checked by the condition.

Linear algorithm Program pokupka; Usescrt; Var a, b, d, den: real; ostatok: real; begin clrscr; write("enter the cost of gloves, briefcase and tie"); readln(a, b, d); write("enter the amount of money you have"); readln(den); oststok:= den – a – b – c; writeln ("after purchase you will have ", ostatok:5:2, "rub."); readln; end.

Y then writeln (x) (if x is greater than y, then print x) else writeln (y) (otherwise we print" title="Branching algorithm Program (name); Var x, y: integer; (input numbers) Begin writeln("Введите 2 числа "); {вводим два целых числа через пробел} readln(x,y); if x>y then writeln (x) {если х больше y, то выводим х} else writeln (y) {иначе выводим" class="link_thumb"> 11 !} Branching algorithm Program (name); Var x, y: integer; (entered numbers) Begin writeln("Enter 2 numbers "); (enter two integers separated by a space) readln(x,y); if x>y then writeln (x) (if x is greater than y, then print x) else writeln (y) (otherwise print y) End. y then writeln (x) (if x is greater than y, then output x) else writeln (y) (otherwise output"> y then writeln (x) (if x is greater than y, then output x) else writeln (y) (otherwise output y) End."> y then writeln (x) (if x is greater than y, then print x) else writeln (y) (otherwise print" title="Branching algorithm Program (name); Var x, y: integer; (input numbers) Begin writeln("Введите 2 числа "); {вводим два целых числа через пробел} readln(x,y); if x>y then writeln (x) {если х больше y, то выводим х} else writeln (y) {иначе выводим"> !}
y then writeln (x) (if x is greater than y, then print x) else writeln (y) (otherwise we print" title="Branching algorithm Program (name); Var x, y: integer; (input numbers) Begin writeln("Введите 2 числа "); {вводим два целых числа через пробел} readln(x,y); if x>y then writeln (x) {если х больше y, то выводим х} else writeln (y) {иначе выводим"> !}

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CONTENTS OF PRESENTATION History. The concept of algorithm. Examples of algorithms. Algorithm executors. What is a program? Properties of the algorithm. Types of algorithms. Methods for describing algorithms. The main blocks of a graphical description of the algorithm. Home © Nechaeva Olga Ivanovna 2006 History of origin. The concept of algorithm. Examples of algorithms. Algorithm executors. What is a program? Properties of the algorithm. Types of algorithms. Methods for describing algorithms. The main blocks of a graphical description of the algorithm. To main

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A LITTLE HISTORY The founder of algebra, the term “algorithm” comes from his name. In world science he was known for his treatise on mathematics, based on the positional principle. Thanks to the translation of this work from Arabic into Latin, “Arabic” numbers entered world mathematics forever. The author's name in the Latinized form Algorismus and Algorithmus originally gave the name to the rules of four arithmetic operations in the decimal number system. Subsequently, the word “algorithm” began to mean any regular process that, in a finite number of steps, provides a solution to a certain class of problems. Al-Khorezmi (786-850 AD) - © Nechaeva Olga Ivanovna 2006

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An algorithm is a set of rules for performing certain actions that ensure the solution of a problem. A L G O R I T M In life, we constantly perform different algorithms. © Nechaeva Olga Ivanovna 2006 We create a daily routine in order to get a lot done. The concept of algorithm is one of the fundamental ones in computer science.

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EXAMPLES OF ALGORITHMS We take out a cookbook and strictly follow the recipe written in it so that the dish is successful and you can treat your friends. We follow traffic rules when crossing the street. © Nechaeva Olga Ivanovna 2006

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PERFORMERS OF ALGORITHMS The algorithm is compiled taking into account the performer. The performer can be a person, an automatic machine, or a computer. © Nechaeva Olga Ivanovna 2006

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PROGRAM © Nechaeva Olga Ivanovna 2006 Each performer has his own command system (SCS). A program is an algorithm written in the language of the performer. Let's look at an example: let's take the training performer Turtle. Let this performer have three commands: forward (1 cm), right (900), left (900). Initial position of the performer: The program code will look like this: left (900) forward (1 cm) forward 1 cm to the right (900) forward (1 cm) What program code should be written for the Turtle to draw the letter G?

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© Nechaeva Olga Ivanovna 2006 PROPERTIES OF THE ALGORITHM (Requirements for compiling the algorithm) Discreteness. The process of solving a problem must be divided into a sequence of individual steps. Unambiguousness (accuracy). The algorithm's commands must be precisely defined (for example, you cannot write 3-4 cups of flour, you must specify 3 cups). Productivity. After executing all the commands of the algorithm, the result should be obtained. Universality (mass appeal). An important property when solving problems on a computer. The algorithm must be applicable to solve not one specific problem, but rather a certain class of problems. For example, to solve a quadratic equation with different coefficients). Clarity. The algorithm must be written in a language understandable to the performer.

Slide 9

Linear. The commands of such an algorithm are executed sequentially from top to bottom. For example, finding the hypotenuse of a right triangle using its two legs. TYPES OF ALGORITHMS © Nechaeva Olga Ivanovna 2006 Branching. Depending on the conditions set, the algorithm allows you to choose one of the options for solving the problem. Examples could be finding the roots of a quadratic equation or a hero at a crossroads from Russian fairy tales. Cyclical. The algorithm contains repetitive actions. For example, when memorizing a poem, you have to reread and repeat the same lines.