Suppose you have a stack in which the values 1 through 5 must be pushed on the stack in th...

Suppose you have a stack in which the values 1 through 5 must be pushed on the stack in that order, but that an item on the stack can be popped and printed at any time. So for example, the operations

Railroad switching system for Exercise 4

s.push(3)

s.push(4)

print s.pop()

s.push(5)

print s.pop()

print s.pop()

print s.pop()

produce the sequence 2 4 5 3 1. Based on the constraints mentioned above, give the list of operations that would produce each of the following sequences. If it is not possible, state so.

a. 1 3 5 4 2

b. 2 3 4 5 1 C. 1 4 3 5 2

d. 1 5 4 2 3

e. Are there sequences that cannot occur? Explain why or why not.