|
| 1 | +''' |
| 2 | +Exercise 20: Element Search |
| 3 | + |
| 4 | +Write a function that takes an ordered list of numbers (a list |
| 5 | +where the elements are in order from smallest to largest) and |
| 6 | +another number. The function decides whether or not the given |
| 7 | +number is inside the list and returns (then prints) an |
| 8 | +appropriate boolean. |
| 9 | + |
| 10 | +Extras: |
| 11 | +Use binary search. |
| 12 | + |
| 13 | +''' |
| 14 | + |
| 15 | +# Solution |
| 16 | +def search_in_simple(number_list, query): |
| 17 | + """ |
| 18 | + Search query in number_list or not. |
| 19 | + |
| 20 | + Arguments: |
| 21 | + number_list -- a list contain all the elements. |
| 22 | + query -- a element |
| 23 | + |
| 24 | + Returns: |
| 25 | + True/False -- if query in number_list return True, else return False |
| 26 | + """ |
| 27 | + if query in number_list: |
| 28 | + return True |
| 29 | + else: |
| 30 | + return False |
| 31 | + |
| 32 | +def search_in_binary(number_list, start, end, query): |
| 33 | + """ |
| 34 | + Search query in number_list or not. |
| 35 | + |
| 36 | + Arguments: |
| 37 | + number_list -- a list contain all the elements. |
| 38 | + start -- start index. |
| 39 | + end -- end index. |
| 40 | + query -- a element. |
| 41 | + |
| 42 | + Returns: |
| 43 | + True/False -- if query in number_list return True, else return False |
| 44 | + """ |
| 45 | + if start > end: |
| 46 | + return False |
| 47 | + mid = int(start + (end - start) / 2) |
| 48 | + if number_list[mid] > query: |
| 49 | + return search_in_binary(number_list, start, mid - 1, query) |
| 50 | + if number_list[mid] < query: |
| 51 | + return search_in_binary(number_list, mid + 1, end, query) |
| 52 | + return True |
| 53 | + |
| 54 | +def main(): |
| 55 | + number_list = [1, 2, 3, 4, 6, 7, 8, 9] |
| 56 | + query1 = 4 |
| 57 | + query2 = 5 |
| 58 | + print(search_in_simple(number_list, query1)) |
| 59 | + print(search_in_binary(number_list, 0, len(number_list), query1)) |
| 60 | + print(search_in_simple(number_list, query2)) |
| 61 | + print(search_in_binary(number_list, 0, len(number_list), query2)) |
| 62 | + |
| 63 | +if __name__ == "__main__": |
| 64 | + main() |
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