Min Stack 2021-09-22 20:00

class MinStack {
    private Stack<Integer> mainStack = new Stack<>();
    private Stack<Integer> minStack = new Stack<>();
    /**
     * initialize your data structure here.
     */
    public MinStack() {

    }

    public void push(int val) {
        mainStack.push(val);
        if(minStack.isEmpty()){
            minStack.push(val);
        }else{
            int min = Math.min(minStack.peek(),val);
            minStack.push(min);
        }
    }

    public void pop() {
        minStack.pop();
        mainStack.pop();
    }

    public int top() {
        return mainStack.peek();
    }

    public int getMin() {
        return minStack.peek();
    }
}