sort and stack

Author: Your Name

AlgorithmAndDataStructure/Basic/sort.py

@@ -0,0 +1,103 @@
+"""按特定顺序对一串数据进行排序。
+排序算法的稳定性，让相等键值的记录维持次序，例如：
+(3,1)(3,7)(4,1)(5,6)维持次序
+(3,7)(3,1)(4,1)(5,6)次序被改变"""
+
+"""Bubble Sort冒泡排序,第一次冒泡把最大的推到最上面，
+第二次把第二大的推到最大的后面，最多需要冒泡的次数为
+元素总数减1"""
+def bubble_sort(list):
+	"""j为每次遍历需要比较的次数，逐次减小1"""
+	for j in range(len(alist)-1,0,-1):
+		for i in range(j):
+			if alist[i] > alist[i+1]:
+				alist[i], alist[i+1] = alist[i+1], alist[i]
+
+"""Selection sort选择排序：包括如何选出列表中的
+最小值"""
+def selection_sort(alist):
+	n = len(alist)
+	"""需要进行次n-1选择操作，逐次找出
+	最大，次最大，，，，"""
+	for i in range(n-1):
+		"""记录最小的位置"""
+		min_index = i
+		"""从i+1位置开始选出最小数据"""
+		for j in range(i+1, n):
+			if alist[j] < alist[min_index]:
+				min_index = j
+		"""如果选出的数据不在正确位置，进行交换"""
+		if min_index != i:
+			alist[i], alist[min_index] = alist[min_index], alist[i]
+
+"""Insertion Sort插入排序"""
+def insert_sort(alist):
+	"""从第二个位置，即下标为1的元素开始向前插入"""
+	for i in range(1, len(alist)):
+		for j in range(i, 0, -1):
+			"""从第i个元素向前比较，如果小于前一个元素，交换位置"""
+			if alist[j] < alist[j-1]:
+				alist[j], alist[j-1] = alist[j-1], alist[j]
+
+"""Quick sort快速排序"""
+def quick_sort(alist, start, end):
+	if start >= end:
+		return
+
+	mid = alist[start]
+	low = start
+	high = end
+
+	while low < high:
+		while low < high and alist[high] >= mid:
+			high -= 1
+			alist[low] = alist[high]
+
+		while low < high and alist[low] < mid:
+			low += 1
+		alist[high] = alist[low]
+	alist[low] = mid
+	quick_sort(alist, start, low-1)
+	quick_sort(alist, low+1, end)
+			
+"""Shell sort希尔排序，是改进版直接插入排序算法"""
+def shell_sort(alist):
+	n = len(alist)
+	gap = n / 2
+	while gap > 0:
+		for i in range(gap, n):
+			j = i
+			while j>= gap and alist[j-gap] > alist[j]:
+				alist[j-gap], alist[j] = alist[j], alist[j-gap]
+				j -= gap
+		gap = gap / 2
+
+"""merge_sort归并排序"""
+def merge_sort(alist):
+	if len(alist) <= 1:
+		return alist
+	num = len(alist)/2
+	left = merge_sort(alist[:num])
+	right = merge_sort(alist[num:])
+	return merge_sort(left, right)
+
+def merge(left, right):
+	l, r = 0, 0
+	result = []
+	while l<len(left) and r<len(right):
+		if left[l] < right[r]:
+			result.append(left[l])
+			l += 1
+		else:
+			result.append(right[r])
+			r += 1
+	result += left[l:]
+	result += right[r:]
+	return result
+
+		
+				
+
+			
+		
+

AlgorithmAndDataStructure/Basic/stack.py

@@ -0,0 +1,25 @@
+"""Last in First out"""
+class Stack(object):
+	def __init__(self):
+		self.items = []
+
+	def is_empty(self):
+		return self.items == []
+
+	def push(self, item):
+		self.items.append(item)
+
+	def pop(self):
+		"""弹出元素"""
+		return self.items.pop()
+
+	def peak(self):
+		"""返回栈顶元素"""
+		return self.items[len(self.items)]
+
+	def size(self):
+		"""返回堆栈的大小"""
+		return len(self.items)
+
+		
+