problem155

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155. Min Stack (Easy)

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

Implement the MinStack class:

• MinStack() initializes the stack object.
• void push(val) pushes the element val onto the stack.
• void pop() removes the element on the top of the stack.
• int top() gets the top element of the stack.
• int getMin() retrieves the minimum element in the stack.

 

Example 1:

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:

• -231 <= val <= 231 - 1
• Methods pop, top and getMin operations will always be called on non-empty stacks.
• At most 3 * 104 calls will be made to push, pop, top, and getMin.

Related Topics

[Stack] [Design]

Similar Questions

1. Sliding Window Maximum (Hard)
2. Max Stack (Easy)

Hints

Hint 1

Consider each node in the stack having a minimum value. (Credits to @aakarshmadhavan)

Documentation

Index

• type MinStack
  • func Constructor() MinStack
  • func (this *MinStack) GetMin() int
  • func (this *MinStack) Pop()
  • func (this *MinStack) Push(x int)
  • func (this *MinStack) Top() int

Types

type MinStack

type MinStack struct {
	// contains filtered or unexported fields
}

func Constructor

func Constructor() MinStack

* initialize your data structure here.

func (*MinStack) GetMin

func (this *MinStack) GetMin() int

func (*MinStack) Pop

func (this *MinStack) Pop()

func (*MinStack) Push

func (this *MinStack) Push(x int)

func (*MinStack) Top

func (this *MinStack) Top() int