Package g0101_0200.s0155_min_stack

Class MinStack

java.lang.Object
g0101_0200.s0155_min_stack.MinStack
public class MinStack extends java.lang.Object
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(int 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.

  • Constructor Summary

    Constructors
    Constructor
    Description
    MinStack()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    getMin()
     
    void
    pop()
     
    void
    push(int val)
     
    int
    top()
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • MinStack

      public MinStack()

  • Method Details

    • push

      public void push(int val)

    • pop

      public void pop()

    • top

      public int top()

    • getMin

      public int getMin()