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Quick Sort with python
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# How efficient to get pivot? | |
def get_pivot(array, left, right): | |
# 현재 잘 안되고 있음 | |
if abs(left-right) > 2: | |
mid = len(array) // 2 | |
first = 0 | |
last = len(array) - 1 | |
dic = {first: array[first], | |
mid: array[mid], | |
last: array[right]} | |
min_ = array[first] | |
max_ = array[last] | |
for k, v in dic.items(): | |
if v < min_: | |
min_ = k | |
if v > max_: | |
max_ = k | |
pivot = [k for k, v in dic.items() if not dic[k] or not dic[k]][0] | |
# print('') | |
else: | |
pivot = left | |
pivot = left | |
return pivot | |
def partition(array, left, right): | |
pivot = get_pivot(array, left, right) | |
while True: | |
while array[left] <= array[pivot]: | |
left += 1 | |
while array[right] > array[pivot]: | |
right -= 1 | |
if left < right: | |
array[left], array[right] = array[right], array[left] | |
else: | |
break | |
array[pivot], array[right] = array[right], array[pivot] | |
return right | |
def quicksort(array, begin=0, end=None): | |
if end is None: | |
end = len(array) - 1 | |
if begin >= end: | |
return | |
pivot = partition(array, begin, end) | |
quicksort(array, begin, pivot-1) | |
quicksort(array, pivot+1, end) | |
array = [54,26,93,17,77,31,31,44,55,20] | |
print(array) | |
quicksort(array) | |
print(array) | |
# [17, 20, 26, 31, 31, 44, 54, 55, 77, 93] |
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