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sortAlgo.py
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187 lines (162 loc) · 5.06 KB
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# http://interactivepython.org/courselib/static/pythonds/SortSearch/toctree.html
class myData(object):
def __init__(self, k, v):
self.k, self.v = k, v
aList = [myData(1, 5), myData(1, 6)]
# O(n**2), O(n), O(n*log2(n))
def insert_sort(arr):
for i in range(1, len(arr)):
temp = arr[i]
j = i
while j > 0 and temp < arr[j-1]: # <=?
arr[j] = arr[j-1]
j = j-1
arr[j] = temp
return arr
# O(n**2), O(n**2)
def selection_sort(arr):
for i in range(len(arr)-1):
index = i
for j in range(i, len(arr)):
if arr[j] < arr[index]:
index = j
if index != i:
arr[i], arr[index] = arr[index], arr[i]
return arr
# O(n**2), O(n**2)/O(n)
def bubble_sort(arr):
for i in range(len(arr)):
found = False
for j in range(1, len(arr)-i):
if arr[j-1] > arr[j]:
arr[j-1], arr[j] = arr[j], arr[j-1]
found = True
if not found:
break
return arr
# O(nlog(n)), O(n**2)
def quick_sort(alist):
quickSortHelper(alist,0,len(alist)-1)
def quickSortHelper(alist,first,last):
if first<last:
splitpoint = partition(alist,first,last)
quickSortHelper(alist,first,splitpoint-1)
quickSortHelper(alist,splitpoint+1,last)
def partition(alist,first,last):
pivot = alist[first]
l = first+1
r = last
done = False
while not done:
while l <= r and alist[l] <= pivot:
l = l + 1
while alist[r] >= pivot and r >= l:
r = r - 1
if r < l:
done = True
else:
alist[l], alist[r] = alist[r], alist[l]
alist[first], alist[r] = alist[r], alist[first]
return r
# O(nlog(n)), O(nlog(n)), O(n)
def merge_sort(alist):
# print("Splitting ",alist)
if len(alist)>1:
mid = len(alist)//2
lefthalf = alist[:mid]
righthalf = alist[mid:]
merge_sort(lefthalf)
merge_sort(righthalf)
i=0
j=0
k=0
while i < len(lefthalf) and j < len(righthalf):
if lefthalf[i] < righthalf[j]:
alist[k]=lefthalf[i]
i=i+1
else:
alist[k]=righthalf[j]
j=j+1
k=k+1
while i < len(lefthalf):
alist[k]=lefthalf[i]
i=i+1
k=k+1
while j < len(righthalf):
alist[k]=righthalf[j]
j=j+1
k=k+1
# print("Merging ",alist)
def shell_sort(alist):
sublistcount = len(alist)//2
while sublistcount > 0:
for startposition in range(sublistcount):
gapInsertionSort(alist,startposition,sublistcount)
# print("After increments of size", sublistcount,
# "The list is", alist)
sublistcount = sublistcount // 2
def gapInsertionSort(alist,start,gap):
for i in range(start+gap,len(alist),gap):
currentvalue = alist[i]
position = i
while position>=gap and alist[position-gap]>currentvalue:
alist[position]=alist[position-gap]
position = position-gap
alist[position]=currentvalue
# 堆构建
def build_heap(arr):
length = len(arr)
# 找到最后一个非叶子节点
index = length//2 - 1
# 从最后一个非节点开始依次向上做堆调整
for i in range(index, -1, -1):
heapify(arr, i)
# 堆调整，这里按大顶堆进行调整
def heapify(arr, index):
# 叶子节点无须再做堆调整
if index > len(arr)/2 - 1:
return None
max_index = index
left_child_index = index*2 + 1
right_child_index = index*2 + 2
if left_child_index < len(arr) and arr[left_child_index] > arr[max_index]:
max_index = left_child_index
if right_child_index < len(arr) and arr[right_child_index] > arr[max_index]:
max_index = right_child_index
if arr[max_index] != arr[index]:
temp = arr[max_index]
arr[max_index] = arr[index]
arr[index] = temp
# 递归调整
heapify(arr, max_index)
# 堆排序
def heap_sort(arr):
arr_sorted = []
# 先构建堆
build_heap(arr)
# 交换堆顶元素和堆末尾元素，交换后堆末尾元素为最大值元素
while len(arr) != 0:
temp = arr[0]
arr[0] = arr[len(arr)-1]
arr[len(arr)-1] = temp
arr_sorted.insert(0, arr.pop(len(arr)-1))
# 调整
heapify(arr, 0)
arr[:] = []
arr.extend(arr_sorted)
if __name__ == '__main__':
iterObj = [1, 9, 7, 3, 2, 0, 81, 9, 32, 2, 6]
exp = [0, 1, 2, 2, 3, 6, 7, 9, 9, 32, 81]
def _assertEqual(a, b, prefix):
msg = 'pass'
if a != b:
msg = 'Error! %s != %s' % (a, b)
print('[%s]: %s' % (prefix, msg))
def _testAlgo(algo):
arr = list(iterObj)
algo(arr)
_assertEqual(arr, exp, algo.__name__)
selfMod = __import__(__name__)
algoList = [v for k,v in selfMod.__dict__.items()
if k.endswith('_sort') and callable(v)]
list(map(_testAlgo, algoList))