DSA · Theory

Stack Permutations (Check if an array is stack permutation of other)

Theory

757/810

Stack Permutations (Check if an array is stack permutation of other)

Stack Permutations (Check if an array is stack permutation of other) is a DSA topic. In plain words you use it for undo typing in a tiny editor. Don’t start with a slogan — start with that picture.

Smallest example: push / pop LIFO. Type it, run it, and say what you see. If you can do that from memory, you know Stack Permutations (Check if an array is stack permutation of other).

From the example next to this theory: Stack Permutations (Check if an array is stack permutation of other) — stack is LIFO: push/pop from the same end.

Trap — pop on empty. Fix that before you talk about advanced DSA.

Viva: what is Stack Permutations (Check if an array is stack permutation of other)? Then show push / pop LIFO. Then name the trap.

Diagram

    | 3 |  ← top (pop)
    | 2 |
    | 1 |
    LIFO

Exam tip

What is Stack Permutations (Check if an array is stack permutation of other)? Show this: push / pop LIFO. Trap: pop on empty.

Example

stack = []
stack.append(10)   # push
stack.append(20)
print(stack.pop()) # 20
print(stack[-1])   # peek → 10

Stack Permutations (Check if an array is stack permutation of other) — stack is LIFO: push/pop from the same end.

Short notes

DefStack Permutations (Check if an array is stack permutation of other) — undo typing in a tiny editor.
Rulepush / pop LIFO
Trappop on empty
Usea tiny editor

DSA · Theory

Stack Permutations (Check if an array is stack permutation of other)

← All stacks

Theory

757/810

Stack Permutations (Check if an array is stack permutation of other)

Smallest example: push / pop LIFO. Type it, run it, and say what you see. If you can do that from memory, you know Stack Permutations (Check if an array is stack permutation of other).

From the example next to this theory: Stack Permutations (Check if an array is stack permutation of other) — stack is LIFO: push/pop from the same end.

Trap — pop on empty. Fix that before you talk about advanced DSA.

Viva: what is Stack Permutations (Check if an array is stack permutation of other)? Then show push / pop LIFO. Then name the trap.

Diagram

    | 3 |  ← top (pop)
    | 2 |
    | 1 |
    LIFO

Exam tip

What is Stack Permutations (Check if an array is stack permutation of other)? Show this: push / pop LIFO. Trap: pop on empty.

Example

stack = []
stack.append(10)   # push
stack.append(20)
print(stack.pop()) # 20
print(stack[-1])   # peek → 10

Stack Permutations (Check if an array is stack permutation of other) — stack is LIFO: push/pop from the same end.

Short notes

DefStack Permutations (Check if an array is stack permutation of other) — undo typing in a tiny editor.
Rulepush / pop LIFO
Trappop on empty
Usea tiny editor

Stack Permutations (Check if an array is stack permutation of other)

Example

Short notes

Questions

Stack Permutations (Check if an array is stack permutation of other)

Example

Short notes

Questions