Binary search in Python using recursion
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The document discusses the steps of binary search algorithm to find an element in a sorted array. It provides an example of finding the element 10 in the array [2, 3, 4, 10, 40] and traces the execution steps. It then provides an example of not finding an element, 41, in the same array and traces those execution steps until it returns -1, indicating the element was not found. The document uses pseudocode and diagrams to clearly explain the recursive logic and flow of the binary search algorithm.
![2 3 4 10 40
If arr[mid]==10:
arr[2]==10:
4 = 10
FALSE
LOW HIGHMID](https://image.slidesharecdn.com/binarysearch-200907140429/85/Binary-search-in-Python-using-recursion-3-320.jpg)
![2 3 4 10 40
Elif arr[mid]>x:
arr[2]>10:
4>10:
FALSE
LOW HIGHMID](https://image.slidesharecdn.com/binarysearch-200907140429/85/Binary-search-in-Python-using-recursion-4-320.jpg)
![2 3 4 10 40
arr[3]==10
TRUE
LOW and MID HIGH](https://image.slidesharecdn.com/binarysearch-200907140429/85/Binary-search-in-Python-using-recursion-7-320.jpg)
Binary search in Python using recursion
- 1. GVK CHINMAYA VIDYALAYA SENIOR SECONDARY SCHOOL Kothuru, Indukurupet, SPS Nellore Binary Search Class: 12 Subject: Python Teacher: C Vijaya Kumar B.Tech,MBA
- 2. 2 3 4 10 40 high>=low: 4>=0 TRUE mid=2 LOW HIGHMID
- 3. 2 3 4 10 40 If arr[mid]==10: arr[2]==10: 4 = 10 FALSE LOW HIGHMID
- 4. 2 3 4 10 40 Elif arr[mid]>x: arr[2]>10: 4>10: FALSE LOW HIGHMID
- 5. 2 3 4 10 40 binary(arr,3,4,10) LOW HIGH
- 6. 2 3 4 10 40 binary(arr,3,4,10) If high>=low: 4>=3: TRUE mid=3 LOW,MID HIGH
- 7. 2 3 4 10 40 arr[3]==10 TRUE LOW and MID HIGH
- 8. 2 3 4 10 40 Mid value is returned here LOW and MID HIGH
- 9. 2 3 4 10 40 result=3 LOW and MID HIGH
- 10. 2 3 4 10 40 If 3 not equal to -1: Item found LOW and MID HIGH
- 11. Lets us see the flow of execution of item not found in the same binary search
- 12. 2 3 4 10 40 HIGHLOW def binary(arr,0,4,41):
- 13. 2 3 4 10 40 HIGHLOW If 4>=0: TRUE mid=2 MID
- 14. 2 3 4 10 40 HIGHLOW If 4==41: False MID
- 15. 2 3 4 10 40 HIGHLOW elif 4 > 41: False MID
- 16. 2 3 4 10 40 HIGHLOW binary(arr,3,4,41): MID
- 17. 2 3 4 10 40 HIGHLOW binary(arr,3,4,41):
- 18. 2 3 4 10 40 HIGHLOW and MID If 4 > 3: TRUE mid=3
- 19. 2 3 4 10 40 HIGHLOW and MID elif 10 > 41: FALSE
- 20. 2 3 4 10 40 HIGHLOW and MID binary(arr,4,4,41)
- 21. 2 3 4 10 40 LOW and HIGH binary(arr,4,4,41)
- 22. 2 3 4 10 40 MID,LOW and HIGH If 4 >= 4: TRUE Mid = 4
- 23. 2 3 4 10 40 MID,LOW and HIGH if 40 == 41: FALSE
- 24. 2 3 4 10 40 MID,LOW and HIGH elif 40 > 41: FALSE
- 25. 2 3 4 10 40 MID,LOW and HIGH binary (arr,5,4,41):
- 26. 2 3 4 10 40 HIGH binary (arr,5,4,41): Low = 5 High = 4 X = 41
- 27. 2 3 4 10 40 HIGH If 4>=5: FALSE
- 28. 2 3 4 10 40 HIGH Return -1
- 29. 2 3 4 10 40 HIGH Return -1 (Third Recursive Call)
- 30. 2 3 4 10 40 HIGH Return -1 (Second recursive call)
- 31. 2 3 4 10 40 HIGH Return -1 (First recursive call)
- 32. 2 3 4 10 40 HIGH Result = -1
- 33. 2 3 4 10 40 HIGH If False: Else print(“element not present in array”)