mirror of
https://github.com/prdlk/leetcode.git
synced 2026-11-02 13:12:44 +00:00
57 lines
1.6 KiB
Plaintext
57 lines
1.6 KiB
Plaintext
---
|
|
title: '155. Min Stack'
|
|
description: Design a stack that supports push, pop, top, and retrieving the minimum element in constant time
|
|
sidebar:
|
|
label: 'Min Stack'
|
|
badge: 'Medium'
|
|
---
|
|
|
|
<Badge variant="accent">Stack</Badge>
|
|
|
|
::::warning
|
|
You must implement a solution with O(1) time complexity for each function.
|
|
::::
|
|
|
|
### Example 1:
|
|
- Input: ``
|
|
- Output: ``
|
|
- Explanation: Input `["MinStack","push","push","push","getMin","pop","top","getMin"]` [[],[-2],[0],[-3],[],[],[],[]] Output `[null,null,null,null,-3,null,0,-2]` Explanation MinStack minStack = new MinStack(); minStack.push(-2); minStack.push(0); minStack.push(-3); minStack.getMin(); // return `-3` minStack.pop(); minStack.top(); // return `0` minStack.getMin(); // return `-2`
|
|
|
|
### Constraints:
|
|
|
|
- `-2^31 <= val <= 2^31 - 1`
|
|
- Methods pop, top and getMin operations will always be called on non-empty stacks.
|
|
- At most 3 * 10^4 calls will be made to push, pop, top, and getMin.
|
|
|
|
## Solution
|
|
|
|
```py
|
|
class MinStack:
|
|
def __init__(self):
|
|
self.stack = []
|
|
self.minStack = []
|
|
|
|
def push(self, value: int) -> None:
|
|
self.stack.append(value)
|
|
value = min(value, self.minStack[-1] if self.minStack else value)
|
|
self.minStack.append(value)
|
|
|
|
def pop(self) -> None:
|
|
self.stack.pop()
|
|
self.minStack.pop()
|
|
|
|
def top(self) -> int:
|
|
return self.stack[-1]
|
|
|
|
def getMin(self) -> int:
|
|
return self.minStack[-1]
|
|
|
|
|
|
# Your MinStack object will be instantiated and called as such:
|
|
# obj = MinStack()
|
|
# obj.push(value)
|
|
# obj.pop()
|
|
# param_3 = obj.top()
|
|
# param_4 = obj.getMin()
|
|
```
|