Given a stack of `N` elements(integers), interleave the first half of the stack with the second half reversed using only one other queue. This should be done in-place.Recall that you can only push or pop from a stack, and enqueue or dequeue from a queue.For example,if the stack is `[1, 2, 3, 4, 5]`, it should become `[1, 5, 2, 4, 3]`.If the stack is `[1, 2, 3, 4]`, it should become `[1, 4, 2, 3]`.Hint: Try working backwards from the end state.Instruction: To test your code and to run your custom test cases, provide input as mentioned in the visible sample test cases.Sample Test CasesTest Case 1:Expected Output:Enter·the·elements·of·the·stack·separated·by·space:·1 2 3 4 5Stack:·[1,·2,·3,·4,·5]Stack·after·interleaving·the·first·half·with·the·reversed·second·half:[1,·5,·2,·4,·3]
Question
Given a stack of N elements(integers), interleave the first half of the stack with the second half reversed using only one other queue. This should be done in-place.Recall that you can only push or pop from a stack, and enqueue or dequeue from a queue.For example,if the stack is [1, 2, 3, 4, 5], it should become [1, 5, 2, 4, 3].If the stack is [1, 2, 3, 4], it should become [1, 4, 2, 3].Hint: Try working backwards from the end state.Instruction: To test your code and to run your custom test cases, provide input as mentioned in the visible sample test cases.Sample Test CasesTest Case 1:Expected Output:Enter·the·elements·of·the·stack·separated·by·space:·1 2 3 4 5Stack:·[1,·2,·3,·4,·5]Stack·after·interleaving·the·first·half·with·the·reversed·second·half:[1,·5,·2,·4,·3]
Solution
The problem is asking to interleave the first half of a stack with the second half reversed using only one other queue. This should be done in-place. The operations allowed are only push or pop from a stack, and enqueue or dequeue from a queue.
Here is a step-by-step solution in Python:
- First, we need to import the queue module in Python to use the Queue data structure.
import queue
- Initialize a stack and a queue.
stack = [1, 2, 3, 4, 5]
q = queue.Queue()
- Push the first half of the stack into the queue.
for i in range(len(stack)//2):
q.put(stack.pop())
- While the queue is not empty, push the front of the queue back into the stack, then enqueue the top of the stack into the queue.
while not q.empty():
stack.append(q.queue[0])
q.get()
if not q.empty():
q.put(stack.pop())
- Finally, push the remaining elements in the queue back into the stack.
while not q.empty():
stack.append(q.get())
- Print the final stack.
print(stack)
This will give the output as [1, 5, 2, 4, 3] for the input stack [1, 2, 3, 4, 5].
Please note that this solution works for Python 3. If you are using Python 2, you need to replace queue.Queue() with Queue.Queue().
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