Python实现的几个常用排序算法实例

def directInsertSort(seq):
 “”” 直接插入排序 “””
 size = len(seq)
 for i in range(1,size):
  tmp, j = seq[i], i
  while j > 0 and tmp <seq[j-1]:
   seq[j], j = seq[j-1], j-1
  seq[j] = tmp
 return seq

def directSelectSort(seq):
 “”” 直接选择排序 “””
 size = len(seq)
 for i in range(0,size – 1):
  k = i;j = i+1
  while j <size:
   if seq[j] <seq[k]:
    k = j
   j += 1
  seq[i],seq[k] = seq[k],seq[i]
 return seq

def bubbleSort(seq):
 “””冒泡排序”””
 size = len(seq)
 for i in range(1,size):
  for j in range(0,size-i):
   if seq[j+1] <seq[j]:
    seq[j+1],seq[j] = seq[j],seq[j+1]
 return seq

def _divide(seq, low, high):
 “””快速排序划分函数”””
 tmp = seq[low]
 while low != high:
  while low = tmp: high -= 1
  if low <high:
   seq[low] = seq[high]
   low += 1
  while low <high and seq[low] <=tmp: low +=1
  if low <high:
   seq[high] = seq[low]
   high -= 1
 seq[low] = tmp
 return low

def _quickSort(seq, low, high):
 “””快速排序辅助函数”””
 if low >= high: return
 mid = _divide(seq, low, high)
 _quickSort(seq, low, mid – 1)
 _quickSort(seq, mid +

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1, high)

def quickSort(seq):
 “””快速排序包裹函数”””
 size = len(seq)
 _quickSort(seq, 0, size – 1)
 return seq

def merge(seq, left, mid, right):
 tmp = []
 i, j = left, mid
 while i <mid and j <=right:
  if seq[i] <seq[j]:
   tmp.append(seq[i])
   i += 1
  else:
   tmp.append(seq[j])
   j += 1
 if i <mid: tmp.extend(seq[i:])
 if j <= right: tmp.extend(seq[j:])

 seq[left:right+1] = tmp[0:right-left+1]

def _mergeSort(seq, left, right):
 if left == right:
  return
 else:
  mid = (left + right) / 2
  _mergeSort(seq, left, mid)
  _mergeSort(seq, mid + 1, right)
  merge(seq, left, mid+1, right)

#二路并归排序
def mergeSort(seq):
 size = len(seq)
 _mergeSort(seq, 0, size – 1)
 return seq

if __name__ == ‘__main__’:
 s = [random.randint(0,100) for i in range(0,20)]
 print s
 print “\n”
 print directSelectSort(copy(s))
 print directInsertSort(copy(s))
 print bubbleSort(copy(s))
 print quickSort(copy(s))
 print mergeSort(copy(s))