def reverse(queue: MyQueue, k):
if queue.size() ==0 or queue.size() < k:
return None
s = MyStack()
for i in range(k):
s.push(queue.dequeue())
q1 = MyQueue()
for i in range(k):
q1.enqueue(s.pop())
while queue.is_empty() is False:
q1.enqueue(queue.dequeue())
return q1
def next_greater_element(lst):
s = MyStack()
res = [-1] * len(lst)
for i in range(len(lst) - 1, -1, -1):
while not s.is_empty() and s.top() < lst[i]:
s.pop()
if not s.is_empty():
res[i] = s.top()
s.push(lst[i])
return res
def insert(stack:MyStack, value):
if(stack.is_empty() or value < stack.top()):
stack.push(value)
else:
temp=stack.pop()
insert(stack, value)
stack.push(temp)
def evaluate_post_fix(exp):
stack = MyStack()
try:
for c in exp:
if c.isdigit():
stack.push(c)
else:
right = stack.pop()
left = stack.pop()
result = str(eval(left + c + right))
stack.push(result)
return stack.pop()
except TypeError:
return 'invalid sequence'
class NewQueue:
def __init__(self):
self.main_stack = MyStack()
self.temp_stack = MyStack()
def enqueue(self, value):
self.main_stack.push(value)
return True
def dequeue(self):
if self.temp_stack.is_empty():
if self.main_stack.is_empty():
return None
while self.main_stack.is_empty() is False:
self.temp_stack.push(self.main_stack.pop())
temp = self.temp_stack.pop()
return temp
def dfs_traversal_helper(g: Graph, source, visited):
result = ""
q = MyStack()
q.push(source)
visited[source] = True
while q.is_empty() is False:
current_node = q.pop()
result += str(current_node)
temp: Node = g.array[current_node].head_node
while temp is not None:
if visited[temp.data] is False:
q.push(temp.data)
visited[temp.data] = True
temp = temp.next_element
return result, visited
def is_balanced(exp):
s = MyStack()
for char in exp:
if char in ['{', '(', '[']:
s.push(char)
else:
char1 = s.pop()
if char == ']' and char1 != '[':
return False
if char == '}' and char1 != '{':
return False
if char == ')' and char1 != '(':
return False
if s.is_empty() is False:
return False
return True
def sortStack(stack:MyStack):
tempStack = MyStack()
while stack.is_empty() is False:
value = stack.pop()
if tempStack.top() is not None and value >= int(tempStack.top()):
tempStack.push(value)
else:
while tempStack.is_empty() is False:
stack.push(tempStack.pop())
tempStack.push(value)
while tempStack.is_empty() is False:
stack.push(tempStack.pop())
return stack
def recursive_sort(stack:MyStack):
if stack.is_empty() is False:
value = stack.pop()
recursive_sort(stack)
insert(stack,value)
insert(stack,value)
def insert(stack:MyStack, value):
if(stack.is_empty() or value < stack.top()):
stack.push(value)
else:
temp=stack.pop()
insert(stack, value)
stack.push(temp)
stack = MyStack()
stack.push(2)
stack.push(97)
stack.push(4)
stack.push(42)
stack.push(12)
stack.push(60)
stack.push(23)
print(stack.stack_list)
recursive_sort(stack)
print(stack.stack_list)
def __init__(self):
self.main_stack = MyStack()
self.temp_stack = MyStack()