155. Min Stack

Link

Solution

class MinStack {

    /** initialize your data structure here. */
    Stack<Integer> s;
    int min = Integer.MAX_VALUE;
    public MinStack() {
        s = new Stack<>();
        
    }
    
    public void push(int x) {
        if(x <= min){
            s.push(min);
            min = x;
        }
        s.push(x);
    }
    
    public void pop() {
        if(min == s.peek()){
            s.pop();
            min = s.peek();
        }
        s.pop();
    }
    
    public int top() {
        return s.peek();
    }
    
    public int getMin() {
        return min;
    }
}