leetcode--Min Stack

Design a stack that supports push, pop, 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.

class MinStack {    Stack<Integer> stack1 = new Stack<Integer>();Stack<Integer> stack2 = new Stack<Integer>();public void push(int x) {if(stack2.size()==0||x<stack2.peek()){stack2.add(x);}else{stack2.add(stack2.peek());}        stack1.add(x);    }    public void pop() {    stack2.pop();    stack1.pop();    }    public int top() {      return stack1.peek();    }    public int getMin() {        return stack2.peek();    }}