def get_rectangle(hist, sz):
max_area = 0
idx = 0
st = Stack()
while idx < sz:
if st.top() is None or hist[idx] >= hist[st.top()]:
st.push(idx)
idx += 1
else:
top_ele = st.pop()
current_area = hist[top_ele] * (idx if st.top() is None else
(idx - st.top() - 1))
#print "current_area %s %s"%(hist[top_ele], current_area)
max_area = max(max_area, current_area)
#print "max= %s"%(max_area)
while st.top() is not None:
top_ele = st.pop()
current_area = hist[top_ele] * (idx if st.top() is None else
(idx - st.top() - 1))
max_area = max(max_area, current_area)
print "Max rectangele = %s" % (max_area)
def use_stack():
st = Stack()
for _ in range(10):
st.push(random.randint(0, 50))
st.get_stack()
st.pop()
print st.top()
st.push(67)
st.get_stack()
def preorder_travel2(node):
"""前序遍历，非递归法"""
stack = Stack()
while node is not None or not stack.is_empty():
while node is not None: # 沿左分支下行
print(node, end=" ")
stack.push(node.right) # 右分支入栈
node = node.left # 指针指向左分支
node = stack.pop() # 遇到空树，回溯
def inorder_travel2(node):
"""中序遍历，非递归法"""
stack = Stack()
while node is not None or not stack.is_empty():
while node is not None:
stack.push(node)
node = node.left if node.left is not None else node.right
node = stack.pop()
print(node, end=" ")
node = node.right
def topoSort(self):
st = Stack()
visited = [False] * self.V
for node in self.adj:
if visited[node] == False:
self.DFS(node, visited, st)
while st.empty() == False:
print "%s " % st.pop(),
def postorder_travel2(node):
"""后序遍历，非递归法"""
stack = Stack()
while node is not None or not stack.is_empty():
while node is not None: # 下行循环，直到栈顶元素为空
stack.push(node)
node = node.left if node.left is not None else node.right
node = stack.pop()
print(node, end=" ")
if not stack.is_empty() and stack.top(
).left == node: # 栈非空且当前节点是栈顶的左子节点
node = stack.top().right
else: # 没有右子树或右子树遍历完毕，强迫退栈
node = None
def dfs(self, idx):
st = Stack()
#self.visited[idx] = True
st.push(idx)
while st.empty() is False:
tmp = st.pop()
#print 'node :',tmp
#st.get_stack()
if self.visited[tmp] is False:
print tmp, " ",
self.visited[tmp] = True
for node in self.graph[tmp]:
if self.visited[node] is False:
st.push(node)
def dfs_graph(graph, v0):
"""深度优先图遍历"""
from queue_stack import Stack
vnum = graph.vertex_num()
visited = [0] * vnum # visited 记录已访问顶点
visited[v0] = 1
DFS_seq = [v0] # DFS_seq 记录遍历序列
st = Stack()
st.push((0, graph.out_edges(v0))) # 入栈 (i, edges)
while not st.is_empty(): # 下次访问边edges[i]
i, edges = st.pop()
if i < len(edges):
v, e = edges[i]
st.push((i + 1, edges)) # 下次回来访问边edges[i+1]
if not visited[v]:
DFS_seq.append(v)
visited[v] = 1
st.push((0, graph.out_edges(v)))
return DFS_seq
def decode_str(str):
l = str.__len__()
int_stack = Stack()
str_stack = Stack()
for i in range(l):
if str[i] >= '0' and str[i] <= '9':
num = 0
while (str[i] >= '0' and str[i] <= '9'):
num = num * 10 + (ord(str[i]) - ord('0'))
i += 1
int_stack.push(num)
elif str[i] == '(': #push into char stack and the int multiplier
if str[i - 1] >= '0' and str[i - 1] <= '9':
str_stack.push('(')
else:
int_Stack.push(1)
str_stack.push(')')
elif str[i] == ')': #process
multiplier = int_stack.top()
int_stack.pop()
new_str = ''
while (len(str_stack) != 0 and str_stack.top() != '('):
new_str = str_stack.top() + new_str
str_stack.pop()
str_stack.pop() #popping the (
replicated_str = ''
for j in range(multiplier):
replicated_str += new_str
for j in range(len(replicated_str)):
str_stack.push(replicated_str[j])
else: #normal alphabets, just push them
str_stack.push(str[i])
print(str_stack)