|
| 1 | +def binary_search(array, target): |
| 2 | + left = 0 |
| 3 | + right = len(array) - 1 |
| 4 | + while left <= right: |
| 5 | + mid = (left + right) // 2 |
| 6 | + if array[mid] == target: |
| 7 | + return mid |
| 8 | + if array[mid] < target: |
| 9 | + left = mid + 1 |
| 10 | + else: |
| 11 | + right = mid - 1 |
| 12 | + return left |
| 13 | + |
| 14 | + |
| 15 | + |
| 16 | +################################################################## |
| 17 | + |
| 18 | + |
| 19 | + |
| 20 | +def find_closest_elements(nums, k, target): |
| 21 | + |
| 22 | + # Check if length of nums is same as k |
| 23 | + if len(nums) == k: |
| 24 | + return nums |
| 25 | + |
| 26 | + # Check if target is less than or equal to first element of nums |
| 27 | + if target <= nums[0]: |
| 28 | + return nums[0:k] |
| 29 | + |
| 30 | + # Check if target is greater than or equal to last element of nums |
| 31 | + if target >= nums[-1]: |
| 32 | + return nums[len(nums) - k: len(nums)] |
| 33 | + |
| 34 | + # Find first closest element to target using binary search |
| 35 | + first_closest = binary_search(nums, target) |
| 36 | + |
| 37 | + # Initialize sliding window pointers |
| 38 | + window_left = first_closest - 1 |
| 39 | + window_right = window_left + 1 |
| 40 | + |
| 41 | + # Expand sliding window until equal to k |
| 42 | + while (window_right - window_left -1) < k: |
| 43 | + |
| 44 | + # Move window right |
| 45 | + if window_left == -1: |
| 46 | + window_right += 1 |
| 47 | + continue |
| 48 | + |
| 49 | + # Move window left |
| 50 | + if window_right == len(nums) or abs(nums[window_left] - target) <= abs(nums[window_right] - target): |
| 51 | + window_left -= 1 |
| 52 | + |
| 53 | + # Move window right |
| 54 | + else: |
| 55 | + window_right += 1 |
| 56 | + |
| 57 | + # Return k closest elements |
| 58 | + return nums[window_left + 1 : window_right] |
| 59 | + |
| 60 | + |
| 61 | + |
| 62 | +# Time Complexity = O(logn + k) |
| 63 | +# Space Complexity = O(1) |
| 64 | + |
| 65 | + |
| 66 | + |
| 67 | +################################################################## |
| 68 | + |
| 69 | + |
| 70 | + |
| 71 | +# Driver code |
| 72 | +def main(): |
| 73 | + |
| 74 | + nums = [ |
| 75 | + [1, 2, 3, 5, 6, 7,8], |
| 76 | + [1, 2, 3, 4, 5], |
| 77 | + [1, 2, 4, 5, 6], |
| 78 | + [1, 2, 3, 4, 5, 10] |
| 79 | + ] |
| 80 | + k = [4, 4, 2, 3] |
| 81 | + num = [4, 3, 10, -5] |
| 82 | + for i in range(len(nums)): |
| 83 | + print((i + 1), ".\tThe ", k[i], |
| 84 | + " Closest Elements for the number ", num[i], " in the array ", |
| 85 | + nums[i], " are:", sep="") |
| 86 | + print("\t", find_closest_elements(nums[i], k[i], num[i])) |
| 87 | + print("-" * 100) |
| 88 | + |
| 89 | +if __name__ == '__main__': |
| 90 | + main() |
| 91 | + |
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