Created
September 3, 2018 18:34
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mergesort.py
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| def merge(arr, r, ini, end): | |
| mid = (ini+end) // 2 | |
| left = ini | |
| right = mid+1 | |
| i = ini | |
| while left <= mid and right <= end: | |
| if arr[left] <= arr[right]: | |
| r[i] = arr[left] | |
| left += 1 | |
| else: | |
| r[i] = arr[right] | |
| right += 1 | |
| i += 1 | |
| while left <= mid: | |
| r[i] = arr[left] | |
| i += 1 | |
| left += 1 | |
| while right <= end: | |
| r[i] = arr[right] | |
| i += 1 | |
| right += 1 | |
| while ini <= end: | |
| arr[ini] = r[ini] | |
| ini += 1 | |
| def mergeSort(arr, r, ini, end): | |
| if ini >= end: | |
| return | |
| mid = (ini+end) // 2 | |
| mergeSort(arr, r, ini, mid) # left | |
| mergeSort(arr, r, mid+1, end) # right | |
| merge(arr, r, ini, end) | |
| def sort(arr): | |
| r = [0] * len(arr) | |
| mergeSort(arr, r, 0, len(arr)-1) | |
| arr = [7, 3, 2, 4] | |
| print('orig:, ', arr) | |
| sort(arr) | |
| print('result:, ', arr) | |
| arr = [7, 3, 2, 4, 1] | |
| print('orig:, ', arr) | |
| sort(arr) | |
| print('result:, ', arr) |
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