Leetcode 155. Min Stack Java language

Design a stack that supports push, POPs, top, and retrieving the minimum element in constant Time.push (x)--Push element X  Onto Stack.pop ()--Removes the element on top of the Stack.top ()--Get the top element.getmin ()--Retrieve the minimum element in the stack.   Example:minstack minstack = new Minstack () Minstack.push ( -2); Minstack.push (0); Minstack.push ( -3); Minstack.getmin ();      --Returns-3.minstack.pop (); Minstack.top ();   --Returns 0.minstack.getmin (); --Returns-2.subscribe to see which companies asked this question.

Test instructions: Design a stack with the Min function.

Public class minstack {    private stack<integer> stackdata ;    private stack<integer> stackmin;    /**  Initialize your data structure here. */    public minstack ()  {        stackData=new Stack<Integer> ();         stackMin=new Stack<Integer> ();    }         public void push (int x)  {         if (Stackmin.isempty ()) {             stackmin.push (x);         }else if (x<= Stackmin.peek ()) {            stackmin.push (x);         }        stackdata.push (x);    }     /////here seems a bit of a problem .... Packaging class comparison ....     public void pop ()  {        if ( Stackdata.peek (). Equals (Stackmin.peek ())) {             stackmin.pop ();        }         stackdata.pop ();     }        public  int top ()  {        return stackdata.peek ();     }        public int getmin ()  {         return stackmin.peek ();     }}/** *  your minstack object will be instantiated and caLled as such: * minstack obj = new minstack ();  * obj.push (x) ;  * obj.pop ();  * int param_3 = obj.top ();  * int param_4  = obj.getmin ();  */

PS: Defines a secondary stack. The minimum value to hold for each step. See also left teacher's book P1.

Leetcode 155. Min Stack Java language