Download to read offline
Uploaded byJeff Nelson
Algoritma Dan Flowchart HOW DO WE SOLVE PROBLEMS
The document discusses algorithms and flowcharts. It begins by defining an algorithm as a well-defined set of steps to solve a problem and proceeds to explain the typical components of an algorithm, including problem specification, design, implementation, and analysis. It also discusses different structures that can be used in algorithms, such as sequences (series of steps), selection (conditional branches), and repetition (loops). Examples are provided for each type of structure. The document emphasizes that algorithms should be unambiguous and effectively solve the problem within a reasonable time.
More Related Content
Similar to Algoritma Dan Flowchart HOW DO WE SOLVE PROBLEMS
Algoritma Dan Flowchart HOW DO WE SOLVE PROBLEMS
- 1. 04/10/2014 1 Algoritma dan Flowchart AnggaAkbar Fanani 1 Problem • Pertanyaan atau tugas yang kita cari jawaban dan/atau penyelesaiannya 2 We "just do" Guesswork- and-luck Experience (possibly someoneelse's) Trial-and-error Scientifically" HOW DO WE SOLVE PROBLEMS?
- 2. 04/10/2014 2 The Problem-solving Process 3 Problemspecification Algorithm Program Executable(solution) Design Implementation Compilation Analysis The Problem-solving Process Problem specification Algorithm Program Executable (solution) Analysis Design Implementation Compilation “Doctor, my head hurts“ Patient has elevated pressure in anterior parietal lobe 1. Sterilize cranial saw 2. Anaesthetize patient 3. Remove top of skull 4. Get the big spoon... 5. etc., etc. sterilize(saw,alcohol); raise_hammer(); lower hammer(fast); start(saw); /* etc. etc. */ 0100111010110010101010101001010101010100 11001010101010100101101001110101010101 00100101110100111101010101111101010100 0110100001101... 4
- 3. 04/10/2014 3 5 Definisi Algoritma • Algoritmaadalah urutan langkah logis tertentu untuk memecahkan suatu masalah ▫ Urutan langkah logis, yang berarti algoritma harus mengikuti suatu urutan tertentu, tidak boleh melompat-lompat • Alur pemikiran dalam menyelesaikan suatu pekerjaan yang dituangkan secara tertulis. ▫ Alur pikiran, sehingga algoritma seseorang dapat juga berbeda dari algoritma orang lain ▫ Tertulis, yang artinya dapat berupa kalimat, gambar, atau tabel tertentu 6
- 4. 04/10/2014 4 Definisi Algoritma • Deretanlangkah-langkah komputasi yang mentransformasikan data masukan menjadi keluaran • Deretan instruksi yang jelas untuk memecahkan masalah, yaitu untuk memperoleh keluaran yang diinginkan dari suatu masukan dalam jumlah waktu yang terbatas • Prosedur komputasi yang terdefinisi dengan baik yang menggunakan beberapa nilai sebagai masukan dan menghasilkan beberapa nilai yang disebut keluaran. 7 Sejarah Algoritma • Asal kata algoritma berasal dari nama Abu Ja’far Mohammed Ibn Musa al-Khowarizmi ▫ Ilmuan Persia yang menulis kitab al jabar wal- muqabala (the book of restoration and reduction) ▫ Tahun 825 M • Perubahan kata ▫ Algorism proses menghitung dengan angka Arab ▫ Algorist orang yang menggunakan angka Arab ▫ Algorithm metode perhitungan secara umum • Tahun 1950 euclid’s algorithm ▫ Langkah-langkah menemukan pembagi bersama terbesar (common greatest divisor = gcd) 8
- 5. 04/10/2014 5 Ciri Algoritma (DonaldE. Knuth) • Finiteness: Algoritma harus berhenti setelah mengerjakan sejumlah langkah terbatas • Definiteness: Setiap langkah harus didefinisikan secara tepat dan tidak berarti-dua (ambiguous) • Algoritma memiliki nol atau lebih masukan (input) • Algoritma memiliki nol atau lebih keluaran (output) • Effectiveness: Algoritma harus efektif, setiap langkah harus sederhana sehingga dapat dikerjakan dalam sejumlah waktu yang masuk akal 9 Algorithm -- Examples • A cooking recipe • Assembly instructions for a model • The rules of how to play a game • VCR instructions • Description of a martial arts technique • Directions for driving from A to B • A knitting pattern • A car repair manual 10
- 6. 04/10/2014 6 Almond and HoneySlice 1/2 quantity Shortcrust Pastry 185 g unsalted butter 100 g castor sugar 5 tablespoonshoney 50 ml cream 50 ml brandy or any other liqueuror spirit 300 g flaked almonds Preheat oven for 200° C Line a 30 cm 20 cm baking tray with baking paper, and then with pastry Bake blind for 20 minutes, then remove weights and foil Turn oven up to 220° C. Bring remaining ingredients to a boil, stirring. Spread evenly over pastry. Bake until topping is bubblingand has caramelised evenly, about 15 minutes. Cool before cuttinginto fingers or squares. 11 From:Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria,1996, p. 349. Almond and Honey Slice 1/2 quantity Shortcrust Pastry 185 g unsalted butter 100 g castor sugar 5 tablespoonshoney 50 ml cream 50 ml brandy or any other liqueuror spirit 300 g flaked almonds Preheat oven for 200° C Line a 30 cm 20 cm baking tray with baking paper, and then with pastry Bake blind for 20 minutes, then remove weights and foil Turn oven up to 220° C. Bring remaining ingredients to a boil, stirring. Spread evenly over pastry. Bake until topping is bubblingand has caramelised evenly, about 15 minutes. Cool before cuttinginto fingers or squares. 12 From:Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria,1996, p. 349. Instructions are given in the order in which they are performed (“executed”)
- 7. 04/10/2014 7 Correct Algorithm? Cut chickeninto pieces and brown the pieces on all sides in a casserole dish in hot olive oil. Remove the chicken and to the juices in the casserole add garlic, onions and green peppers, and sauté until onion is golden. Add bay leaf, whole tomatoes, and chicken broth. When the broth boils add salt, saffron and rice. Arrange chicken on rice, cover casserole and bake in a moderate oven (350°F) for 20 minutesor until the rice is tender. Add beans and artichokes during last 10 minutesof cooking. 13 From: “Arroz Con Pollo” in The Margaret Fulton Cookbook, Hamlyn, Sydney, 1968. Correct Algorithm? Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil. Remove the chicken and to the juices in the casserole add garlic, onions and green peppers, and sauté until onion is golden. Add bay leaf, whole tomatoes, and chicken broth. When the broth boils add salt, saffron and rice. Arrange chicken on rice, cover casserole and bake in a moderate oven (350°F) for 20 minutesor until the rice is tender. Add beans and artichokes during last 10 minutesof cooking. 14 From: “Arroz Con Pollo” in The Margaret Fulton Cookbook, Hamlyn, Sydney, 1968.
- 8. 04/10/2014 8 Correct Algorithm? Cut chickeninto pieces and brown the pieces on all sides in a casserole dish in hot olive oil. Remove the chicken and to the juices in the casserole add garlic, onions and green peppers, and sauté until onion is golden. Add bay leaf, whole tomatoes, and chicken broth. When the broth boils add salt, saffron and rice. Arrange chicken on rice, cover casserole and bake in a moderate oven (350°F) for 10 minutes. Add beans and artichokes. Cover, and bake for another 10 minutesor until rice is tender. 15 Correct algorithm ???... 16
- 9. 04/10/2014 9 Correct algorithm 17 Values • Representquantities, amounts or measurements • May be numerical or alphabetical (or other things) • Often have a unit related to their purpose • Example: ▫ Recipe ingredients 18
- 10. 04/10/2014 10 Variables • Are containersfor values – places to store values • Example: 19 This jar can contain 10 cookies 50 grams of sugar 3 slices of cake etc. Values Variable Restrictions on Variables • Variables may be restricted to contain a specific type of value 20
- 11. 04/10/2014 11 Instructions (Primitives) • Someaction that is ▫ simple ▫ unambiguous ▫ that the system knows about... ▫ ...and should be able to actually do 21 Instructions – Examples • Take off your shoes • Count to 10 • Cut along dotted line • Knit 1 • Purl 2 • Pull rip-cord firmly • Sift 10 grams of arsenic 22 Directions to perform specific actions on values and variables
- 12. 04/10/2014 12 Instructions -- Application •Some instructions can only be applied to a specific type of values or variables • Examples: 23 Instructions (Primitives) -- Recommendations • When writing an algorithm, make each instruction simple and unambiguous • Example: 24 Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil. Cut chicken into pieces. Heat olive oil in a casserole dish. Brown the chicken pieces in the casserole dish.
- 13. 04/10/2014 13 Instructions (Primitives) • Whenwriting an algorithm, make each instruction simple and unambiguous • Example: 25 Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil. Cut chicken into pieces. Heat olive oil in a casserole dish. Brown the chicken pieces in the casserole dish. A “sequence” of simple instructions Function • A named sequence of instructions • So that you can ▫ Refer to it collectively (by name) ▫ ...instead of individually (by each instruction in the sequence) • Example: ▫ Drive_To_Uni 26
- 14. 04/10/2014 14 Function -- Example functionDrive_To_Uni { 1. find car keys 2. disable car alarm 3. open car door 4. get in car 5. shut car door 6. put keys in ignition 7. start car 8. back car out of driveway 9. drive to end of street 10. turn right 11. drive to end of street 12. turn left ...etc...etc...etc 27 ...etc...etc...etc... 52. find parking space 53. pull into parking space 54. turn off engine 55. remove keys from ignition 56. open car door 57. get out 58. shut car door 59. lock car door 60. enable alarm } Function – Example function Do_Wednesday { Wake_up Have_Shower Eat_Breakfast Drive_To_Uni Sit_1301_Lecture ...etc...etc...etc... Drive_From_Uni ...etc...etc...etc... } function Do_Week { Do_Monday Do_Tuesday Do_Wednesday Do_Thursday ...etc...etc...etc... } 28
- 15. 04/10/2014 15 Components of anAlgorithm • Variables and values • Instructions ▫ Sequences ▫ Functions ▫ Selections ▫ Repetitions Also required: Documentation 29 Struktur dasar algoritma Struktur Urut (Sequence), Struktur Pemilihan (Selection), Struktur Pengulangan (Repetition). 30
- 16. 04/10/2014 16 Sequence • A seriesof instructions • ...to be carried out one after the other... • ...without hesitation or question • Example: ▫How to cook a Gourmet MealTM 31 Sequence -- Example 1. Open freezer door 2. Take out Gourmet Meal™ 3. Close freezer door 4. Open microwave door 5. Put Gourmet Meal™ on carousel 6. Shut microwave door 7. Set microwave on high for 5 minutes 8. Start microwave 9. Wait 5 minutes 10.Open microwave door 11.Remove Gourmet Meal™ 12.Close microwave door 32
- 17. 04/10/2014 17 Struktur Urut (Sequence) •suatu strukturprogram dimana setiap baris program akan dikerjakan secara urut dari atas ke bawah sesuai dengan urutan penulisannya. • instruksibaris program 2 akan dikerjakan jika instruksi baris program 1 telah selesai dikerjakan. 33 Selection • An instruction that decides which of two possible sequences is executed • The decision is based on a single true/false condition • Examples: ▫ Car repair ▫ Reciprocals 34
- 18. 04/10/2014 18 Selection Example –Car Repair if (motor turns) then { CheckFuel CheckSparkPlugs CheckCarburettor } else { CheckDistributor CheckIgnitionCoil } 35 Selection Example – Car Repair if (motor turns) then { CheckFuel CheckSparkPlugs CheckCarburettor } else { CheckDistributor CheckIgnitionCoil } 36 Should be a true or false condition
- 19. 04/10/2014 19 Selection Example –Car Repair if (motor turns) then { CheckFuel CheckSparkPlugs CheckCarburettor } else { CheckDistributor CheckIgnitionCoil } 37 Sequence if the condition is true Selection Example – Car Repair if (motor turns) then { CheckFuel CheckSparkPlugs CheckCarburettor } else { CheckDistributor CheckIgnitionCoil } 38 Sequence if the condition is false
- 20. 04/10/2014 20 Struktur Pemilihan (Selection), •Menghasilkan nilai benar (true) atau nilai salah (false). • IF sederhana IF <syarat> THEN <instruksi> • Pada bentuk IF sederhana ini, intruksi akan dikerjakan jika syarat yangdiuji benilai benar (true). Jika syarat yang diuji benilai salah (false) maka tidak ada instruksi yang dikerjakan. 39 IF … THEN … ELSE … • IF <syarat> THEN <instruksi1> ELSE <instruksi2> • Pada bentuk ini terdapat dua kemungkinan pilihan yang akan dikerjakan berdasarkan hasil pengujian, jika syarat yang diuji benilai benar maka instruksi1 yang dikerjakan, dan jika syarat yang diuji bernilai salah maka instruksi2 yang dikerjakan. 40
- 21. 04/10/2014 21 IF Bersarang (NestedIF) • IF <syarat1> THEN <instruksi1> • ELSE IF <syarat2> THEN <instruksi2> • ELSE IF <syarat3> THEN <instruksi3> • ELSE IF <syaratm> THEN <instruksim> • ELSE <Instruksin> 41 Repetition • Repeat an instruction... ▫ ...while (or maybe until) some true or false condition occurs ▫ Test the condition each time before repeating the instruction • Also known as iteration or loop • Example: ▫ Algorithm for getting a date 42
- 22. 04/10/2014 22 Repetition – Example functionAskOnDate ( name, time, location ) { Phone(name) Say("Hey", name, "it's your lucky day!") Say("Wanna come to", location, "at", time, "?") ListenToReply ( ) start begging count at zero while (reply is "No" and begging count < 100) { Say("Oh please!") add 1 to begging count ListenToReply ( ) } } 43 Repetition – Example (cont) function AskOnDate ( name, time, location ) { Phone(name) Say("Hey", name, "it's your lucky day!") Say("Wanna come to", location, "at", time, "?") ListenToReply ( ) start begging count at zero while ( reply is "No" and begging count < 100 ) { Say("Oh please!") add 1 to begging count ListenToReply ( ) } } 44 Condition is tested before sequence
- 23. 04/10/2014 23 Repetition – Example(cont) function AskOnDate ( name, time, location ) { Phone(name) Say("Hey", name, "it's your lucky day!") Say("Wanna come to", location, "at", time, "?") ListenToReply ( ) start begging count at zero while (reply is "No" and begging count < 100) { Say("Oh please!") add 1 to begging count ListenToReply ( ) } } 45 Sequence may not get executed at all Repetition – Example (cont) function AskOnDate ( name, time, location ) { Phone(name) Say("Hey", name, "it's your lucky day!") Say("Wanna come to", location, "at", time, "?") ListenToReply ( ) start begging count at zero while (reply is "No" and begging count < 100) { Say("Oh please!") add 1 to begging count ListenToReply ( ) } } 46 Ensure initial values of variables used in the conditions are set correctly
- 24. 04/10/2014 24 Repetition – Example(cont) function AskOnDate ( name, time, location ) { Phone(name) Say("Hey", name, "it's your lucky day!") Say("Wanna come to", location, "at", time, "?") ListenToReply ( ) start begging count at zero while (reply is "No" and begging count < 100) { Say("Oh please!") add 1 to begging count ListenToReply ( ) } } 47 Ensure the variables used in the conditions are updated in each repetition Repetition – Example (cont) function AskOnDate ( name, time, location ) { Phone(name) Say("Hey", name, "it's your lucky day!") Say("Wanna come to", location, "at", time, "?") ListenToReply ( ) start begging count at zero while (reply is "No" and begging count < 100) { Say("Oh please!") } } 48 Infinite loop • What if we don’t increment the begging count?
- 25. 04/10/2014 25 Struktur pengulangan repetition •Struktur for • Mengulangsatu baris instruksiatau satu blok instruksisampai jumlah perulanganyang disyaratkanterpenuhi. • Ciri utama terdapatnilai awaldan nilai akhir yang menunjukkanbanyaknya pengulanganyang akan dilakukan. 49 Struktur while • untukmengulangsatu baris instruksi atau satu blok baris instruksi selama syarat yang diberikan masih terpenuhi. • Syarat akan diuji didepan. • Jika syarat yang diuji bernilai benar maka instruksi1,instruksi2, instruksi3 akan dikerjakan, setelah mengerjakan instruksi1, instruksi2, instruksi3 maka syarat akan diuji lagi. • pengulangan akan berhentijika syarat yang diuji bernilai salah. 50
- 26. 04/10/2014 26 Struktur do …while • mengulangsatu baris instruksi atau satu blok baris instruksi sampai syarat tidak terpenuhi. • syarat akan diuji dibelakang, sehinggabaris instruksi yang masukdalam blok do…while minimal akan dikerjakan satu sekali. 51 Documentation • Records what the algorithm does • Describes how it does it • Explains the purpose of each component of the algorithm • Notes restrictions or expectations • Example: ▫ Getting a date (again) 52
- 27. 04/10/2014 27 Documentation -- Example Thinkof something romantic to do decide on time and location Work through address book to look for a person initialise booking to “unsuccessful” until (successfully booked) { get next Name in little black book AskOnDate(Name, Time, Location) DetermineBookingSuccess } Assumes that I will find someone in the book before it runs out SighWithRelief 53 From Algorithms to Programs 54 Problem Program Program Algorithm Algorithm: A sequence of instructions describing how to do a task (or process)
- 28. 04/10/2014 28 The Software DevelopmentProcess • Define the problem clearly • Analyse the problem thoroughly • Design an algorithm carefully • Code the algorithm efficiently • Test the code thoroughly • Document the system lucidly 55 Top-down Algorithm Design • Write down what you have to do • Break that into 3-7 smaller steps • Break each step into 3-7 smaller steps • Keeping subdividing until each individual step is easy enough to do • Example: ▫ Learning 56
- 29. 04/10/2014 29 Top-down Design --Example 57 Learn Prepare Study Reinforce Read Make notes Prepare questions Attend lecture Listen and think Complete prac Attend tute Record answers to questions Revise notes Read lecture notes Read textbook Read exercise Design algorithm Code solution Test and document Record insights Cara Penyajian Algoritma • Uraian Deskriptif ▫ Menggunakan bahasa yang bisa di gunakan sehari- hari • Menggunakan flow chart (diagram alir) • Menggunakan pseudo-code ▫ Ditulis dalam kode-kode yang disepakati yang mempunyai arti 58
- 30. 04/10/2014 30 59 Algoritma dan Flowchart •Algoritma merupakan urutan langkah logika pemikiran detail yang diperlukan untuk memecahkan masalah. • Algoritma dapat direpresentasikan dalam format grafis yang disebut flowchart atau diagram alir. • Flowchart juga dapat digunakan untuk menggambarkan aliran urutan program 60
- 31. 04/10/2014 31 Bagan-bagan Flowchart • Terminal ▫Bentuk : rounded rectangle ▫ Mengindikasikan titik awal atau akhir 61 Bagan-bagan Flowchart • Connector ▫ Bentuk : circle ▫ Mengindikasikan titik penghubung ke bagan lain yang terputus dalam satu halaman karena terlalu jauh atau memungkinkan memotong garis panah lain 62
- 32. 04/10/2014 32 Bagan-bagan Flowchart • Connector ▫Bentuk : pentagon ▫ Mengindikasikan titik penghubung ke bagan lain yang terputus karena beda halaman 63 Bagan-bagan Flowchart • Preparation atau initialization ▫ Bentuk : hexagon ▫ Mengindikasikan tahap awal pemrograman (misalnya mendeklarasikan variabel, mengidentifikasikan nilai awal konstanta atau variabel) 64
- 33. 04/10/2014 33 Bagan-bagan Flowchart • Data ▫Bentuk : parallelogram ▫ Mengindikasikan masukan atau keluaran data 65 Bagan-bagan Flowchart • Process ▫ Bentuk : rectangle ▫ Mengindikasikan proses komputasi 66
- 34. 04/10/2014 34 Bagan-bagan Flowchart • Predefined/NestedProcess (Subroutine) ▫ Bentuk : rectangle ▫ Mengindikasikan proses komputasi 67 Bagan-bagan Flowchart • Manual Operation ▫ Bentuk : trapezoid ▫ Mengindikasikan operasi yang dilakukan secara manual 68
- 35. 04/10/2014 35 Bagan-bagan Flowchart • ManualInput ▫ Bentuk : trapezoid ▫ Mengindikasikan masukan manual menggunakan input device (misalnya keyboard, mouse, bar code reader, imaging device) 69 Bagan-bagan Flowchart • Card ▫ Bentuk : chamfered rectangle ▫ Mengindikasikan penggunaan card reader (misalnya punched card reader ataupun memory card reader) 70
- 36. 04/10/2014 36 Bagan-bagan Flowchart • Databaseatau Repository ▫ Bentuk : drum ▫ Mengindikasikan penggunaan media penyimpanan basisdata 71 Bagan-bagan Flowchart • Display ▫ Bentuk : CRT Symbol ▫ Mengindikasikan proses penampilan informasi untuk dibaca atau dilihat user di layar monitor atau projector 72
- 37. 04/10/2014 37 Bagan-bagan Flowchart • Report ▫Bentuk : Sheet ▫ Mengindikasikan proses pencetakan laporan untuk dibaca atau dilihat user menggunakan printer atau plotter 73 Bagan-bagan Flowchart • Annotation ▫ Bentuk : Arrow ▫ Mengindikasikan hubungan presedensi antar operasi atau alur urutan operasi 74
- 38. 04/10/2014 38 Bagan-bagan Flowchart • Decision ▫Bentuk : diamond ▫ Mengindikasikan pencabangan alternatif operasi dengan pengambilan keputusan berdasarkan kriteria atau kondisi 75 Decision / Condition Structure 76 YES NO YES NO YES NO YES NO
- 39. 04/10/2014 39 Repetition / RecursiveStructure 77 YES NO YES NO Metodologi Pengembangan Program 78 Mulai Analisis Domain Masalah Merumuskan Algoritma Semua Skenario Tertulis ? Mapping Flowchart Struktur Logika Sesuai ? Verify Program Code Identifier, Syntax, Semantic ? Debug Listing Program Compile Machine Code Compile Berhasil ? Eksekusi Program Eksekusi Berhasil ? Keluaran Program Sesuai ? Eksekusi Program Selesai
- 40. 04/10/2014 40 Contoh Algoritma Step 1:Turn the stereo on. Step 2: If the band is set to FM, switch it to AM. Step 3: If the station is set to a station greater than 610, turn the station to the left until 610 is reached. Step 4: If the station is set to a station less than 610, turn the station to the right until 610 is reached. Step 5: Listen to the best sports talk station in the country. 79 80 Contoh Flowchart