Stacks

Question 1

What is a stack

Answer 1

Abstract data type , last in first out

Question 2

Size()

Answer 2

Return top+ 1

Question 3

IsEmpty()

Answer 3

FUNCTION is_empty(top)
IF top == -1 THEN
RETURN True
ELSE
RETURN False
ENDIF
ENDFUNCTION

Question 4

Peek()

Answer 4

FUNCTION peek(stack, top)
IF is_empty(top) == True THEN
PRINT(“Stack is empty - nothing to peek”)
peeked_item = Null
ELSE
peeked_item = stack[top]
ENDIF
RETURN peeked_item
ENDFUNCTION

Question 5

Push(x)

Answer 5

FUNCTION push(stack, top, data)
IF is_full(top) == True THEN
PRINT(“Stack is full”)
ELSE
top = top + 1
stack[top] = data
ENDIF
RETURN top
ENDFUNCTION

Question 6

Pop ()

Answer 6

FUNCTION pop(stack, top)
IF is_empty(top) == True THEN
PRINT (“Stack is empty - nothing to pop”)
popped_item = Null
ELSE
popped_item = stack[top]
top = top - 1
ENDIF
RETURN (popped_item, top)
ENDFUNCTION

Question 7

isfull()

Answer 7

FUNCTION is_full(top)
IF top == MAX_SIZE - 1 THEN
RETURN True
ELSE
RETURN False
ENDIF
ENDFUNCTION