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();
}
}