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.

Solution:

class MinStack {
    Stack<Integer> stack;
    int curMin;
    Stack<Integer> minStack;


    public MinStack(){
        stack = new Stack<Integer>();
        curMin = Integer.MAX_VALUE;
        minStack = new Stack<Integer>();
    }


    public void push(int x) {
        stack.push(x);
        if (x<=curMin){
            minStack.push(x);
            curMin = x;
        }
    }

    public void pop() {
        int val = stack.peek();
        stack.pop();
        if (val==curMin){
            minStack.pop();
            if (!minStack.isEmpty())
                curMin = minStack.peek();
            else curMin = Integer.MAX_VALUE;
 
        }
    }

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

    public int getMin() {
        return curMin;        
    }
}