1. 冒泡排序
本文采用兩種方法進行冒泡排序，
第一種：第一次排序後，數組中的第一個元素最小
def bubble_sort(lists):
# 冒泡排序
count = len(lists)
for i in range(count):
for j in range(i + 1, count):
if lists[i] > lists[j]:
lists[i], lists[j] = lists[j], lists[i]
a = [7, 4, 9, 10]
bubble_sort(a)
print a
第二種：第一次排序後，數組中的最後一個元素最大
def bubble_sort(List):
for i in range(len(List)-1):
for j in range(1, len(List)-i):
if List[j-1] > List[j]:
List[j-1], List[j] = List[j], List[j-1]
if __name__ == '__main__':
a = [15,1,9,3,6,8,12,2,0]
bubble_sort(a)
print a
output:
[0, 1, 2, 3, 6, 8, 9, 12, 15]
2.插入排序
def insertSort(num):
for i in range(1, len(num)):
key = num[i]
j = i - 1
while j >= 0:
if num[j] > key:
num[j+1] = num[j]
num[j] = key
j -= 1
a = [2, 7, 5, 4]
insertSort(a)
print a
3.快速排序
def quickSort(arr):
less = []
pivotList = []
more = []
if len(arr) <= 1:
return arr
else:
pivot = arr[0]
for i in arr:
if i < pivot:
less.append(i)
elif i > pivot:
more.append(i)
else:
pivotList.append(i)
less = quickSort(less)
more = quickSort(more)
return less + pivotList + more
a = [5,8,4,7,9,2]
b = quickSort(a)
print a
print b
output:
[5, 8, 4, 7, 9, 2]
[2, 4, 5, 7, 8, 9]
4.二分查找
4.1 打印出所查找值的index
def binary_search(List, t):
if not List:
return
right = len(List) - 1
left = 0
while left <= right:
middle = (right + left) / 2
print "middle value is " + str(List[middle])
if List[middle] > t:
right = middle - 1
elif List[middle] < t:
left = middle + 1
else:
return middle
if __name__ == '__main__':
a = [1, 3, 5, 6, 10, 12, 13, 18, 20, 22]
index = binary_search(a, 6)
print "This index of 6 is %s" % str(index)
output:
middle value is 10
middle value is 3
middle value is 5
middle value is 6
This index of 6 is 3
4.2 返回是否可以在數組中找到該值
def binary_search(List, t):
if not List:
return
while len(List)/2:
middle = len(List)/2
if List[middle] > t:
List = List[:middle]
elif List[middle] < t:
List = List[middle:]
else:
return True
if List[0] == t:
return True
if __name__ == '__main__':
a = [1, 3, 5, 6, 10, 12, 13, 18, 20, 22]
result = binary_search(a, 13)
print result
output: True