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Searching

Searching. Oleh : Tim Teaching Bernadus Anggo Seno Aji, S.Kom., M.Kom Farah Zakiyah Rahmanti, S.ST., M.T. Agustus 2018. Bahan kajian Mata kuliah. Notasi Algoritmik, Tipe Dasar, Nilai , Percabangan Percabangan Perulangan Fungsi UTS. Prosedur Array dan String Searching Sorting

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Searching

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  1. Searching Oleh : Tim Teaching Bernadus Anggo Seno Aji, S.Kom., M.Kom Farah Zakiyah Rahmanti, S.ST., M.T. Agustus 2018

  2. Bahankajian Mata kuliah • Notasi Algoritmik, Tipe Dasar, Nilai, Percabangan • Percabangan • Perulangan • Fungsi • UTS • Prosedur • Array dan String • Searching • Sorting • UAS

  3. Find the maximum / minimum • Maximum = 10 • Maximum = 3

  4. Find the maximum / minimum • Logic : • Asumsielemenpertamaadalahnilaimaksimum • Kemudianbacaelemensisanya • Bandingkan dengan nilaimaksimum yang kita punya saat ini. • Jikanilai dari elemen yang kita proses lebihbesar dari nilaimaksimum, makagantinilaimaksimum yang kita miliki

  5. Find the maximum / minimum Minimum?

  6. Find Where is the maximum / minimum • Dalam proses pencarian suatu nilaididalam array, lokasi/indeknilaitersebutdidalam array lebihpentingdibandingnilai yang dicari itu sendiri. • Karena, jikaindek dari nilaitersebutdiketahui,nilai yang dicari juga bisa didapatkan • Buatalgoritma untuk menampikanposisinilaimaksimum • Maximum position = 3

  7. Find Where is the maximum / minimum

  8. Find a Number Create an algorithm to search a number within an array • Search = 5, output : found • Search = 3, output : not found

  9. Find a Number • Logic : • Read from first to the last element or until the first value found • Example x = 8 X = 8 X = 8 X = 8 X = 8 X = 8

  10. Find a Number • Logic : • Read from first to the last element or until the first value found • Example x = 6 X = 6 X = 6 X = 6 X = 6 X = 6 . . . .

  11. Find a Number (Sequential Search)

  12. Searching in an Ordered Value • Logic : • Read each element until the value is greater or equal to the searched value • Example x = 6 X = 6 X = 6 X = 6 X = 6 X = 6 X = 6 X = 6 No need to search the rest

  13. Searching in an Ordered Value

  14. Binary Search

  15. Binary Search • Logic : • Assume the array is ordered by ascending • Look at the middle value of the array • If the searched value is less than the middle value, then the value, if any, must be at the first half of the array; discard the second half of the array • If the searched value is greater than the middle value, then the value, if any, must be at the second half of the array; discard the first half of the array • Repeat the process until the value found or the array is exhausted

  16. Binary Search • Example x = 51

  17. Binary Search • Example x = 51 • Bottom index = 1 • Top index = 10 • Middle index = ( 1 + 10 ) div 2 = 5 • X > middle  the value, if any, must be at the second half • New bottom index  middle + 1 X = 51

  18. Binary Search • Example x = 51 • Bottom index = 6 • Top index = 10 • Middle index = ( 6 + 10 ) div 2 = 8 • X < middle  the value, if any, must be at the first half • New top index  middle - 1 X = 51

  19. Binary Search • Example x = 51 • Bottom index = 6 • Top index = 7 • Middle index = ( 6 + 7 ) div 2 = 6 • X = middle  value found X = 51

  20. Binary Search • Example x = 25 • Bottom index = 1 • Top index = 10 • Middle index = ( 1 + 10 ) div 2 = 5 • X < middle  the value, if any, must be at the first half • New Top index  middle - 1 X = 25

  21. Binary Search • Example x = 25 • Bottom index = 1 • Top index = 4 • Middle index = ( 1 + 4 ) div 2 = 2 • X > middle  the value, if any, must be at the second half • New Bottom index  middle + 1 X = 25

  22. Binary Search • Example x = 25 • Bottom index = 3 • Top index = 4 • Middle index = ( 3 + 4 ) div 2 = 3 • X < middle  the value, if any, must be at the first half • New Top index  middle - 1 X = 25

  23. Binary Search • Example x = 25 • Bottom index = 3 • Top index = 3 • Middle index = ( 3 + 3 ) div 2 = 3 • X < middle  the value, if any, must be at the first half • New Top index  middle - 1 X = 25

  24. Binary Search • Example x = 25 • Bottom index = 3 • Top index = 2 • Top < bottom, array exhausted, value not found

  25. Question?

  26. Terima Kasih

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