Copy without reversing
Updated
A naive transfer reverses. To copy in order: copy the backing array slice, or transfer to a helper then to the destination (two reversals), or walk bottom-to-top pushing onto a fresh stack (for array-backed, iterate 0..size-1).
What to focus on
One stack pour is reverse. Two pours is identity. Iterating from the top and pushing would reverse. Know which direction you walk.
Worked examples
slice copy
a = [4, 1, 9]- copy indices 0..2
Result: b [4, 1, 9] top 9
two pours
a = [4, 1, 9] → helper → b- helper [9,1,4]
- b [4,1,9]
Result: order restored
one pour bug
a = [4, 1, 9] → b once- b [9, 1, 4] top 4
Result: reversed — not a copy
Try it
Write copyInOrder(a). a is the stack written bottom to top. Return a copy whose top matches a. Use a slice or two pours. Show that one pour is reversed. a = [4, 1, 9] → b [4, 1, 9] top 9. a = [4, 1, 9] → helper → b → order restored. a = [4, 1, 9] → b once → reversed — not a copy.
The stack is non-empty. Values are integers.