A stack that keeps elements in ascending order (bottom to top). Examples: >>> s = OrderedStack() >>> s.push(3) >>> s.push(1) >>> s.push(2) >>> s.pop() 3
| 16 | |
| 17 | |
| 18 | class OrderedStack: |
| 19 | """A stack that keeps elements in ascending order (bottom to top). |
| 20 | |
| 21 | Examples: |
| 22 | >>> s = OrderedStack() |
| 23 | >>> s.push(3) |
| 24 | >>> s.push(1) |
| 25 | >>> s.push(2) |
| 26 | >>> s.pop() |
| 27 | 3 |
| 28 | """ |
| 29 | |
| 30 | def __init__(self) -> None: |
| 31 | """Initialize an empty ordered stack.""" |
| 32 | self.items: list[int] = [] |
| 33 | |
| 34 | def is_empty(self) -> bool: |
| 35 | """Check if the stack is empty. |
| 36 | |
| 37 | Returns: |
| 38 | True if the stack has no elements. |
| 39 | """ |
| 40 | return self.items == [] |
| 41 | |
| 42 | def _push_direct(self, item: int) -> None: |
| 43 | """Append an item without enforcing order. |
| 44 | |
| 45 | Args: |
| 46 | item: The value to append. |
| 47 | """ |
| 48 | self.items.append(item) |
| 49 | |
| 50 | def push(self, item: int) -> None: |
| 51 | """Push an item while maintaining sorted order. |
| 52 | |
| 53 | Args: |
| 54 | item: The value to push. |
| 55 | """ |
| 56 | temp_stack = OrderedStack() |
| 57 | if self.is_empty() or item > self.peek(): |
| 58 | self._push_direct(item) |
| 59 | else: |
| 60 | while item < self.peek() and not self.is_empty(): |
| 61 | temp_stack._push_direct(self.pop()) |
| 62 | self._push_direct(item) |
| 63 | while not temp_stack.is_empty(): |
| 64 | self._push_direct(temp_stack.pop()) |
| 65 | |
| 66 | def pop(self) -> int: |
| 67 | """Remove and return the top element. |
| 68 | |
| 69 | Returns: |
| 70 | The top (largest) element. |
| 71 | |
| 72 | Raises: |
| 73 | IndexError: If the stack is empty. |
| 74 | """ |
| 75 | if self.is_empty(): |
no outgoing calls