155. Min Stack

class MinStack {
public:
    stack<int> s, mini;

    MinStack() {
    }
    
    void push(int val) {
        //for single element or first insertion
        if(s.empty())  
        {
            mini.push(val);
        }
        else
        {
            mini.push(min(val, mini.top()));
        }
        s.push(val);
    }
    
    void pop() {
        if(s.empty())
        {
            return;
        }
        else
        {
            s.pop();
            mini.pop();
        }
    }
    
    int top() {
        return s.top();
    }
    
    int getMin() {
        return mini.top();
    }
};

/**
 * Your MinStack object will be instantiated and called as such:
 * MinStack* obj = new MinStack();
 * obj->push(val);
 * obj->pop();
 * int param_3 = obj->top();
 * int param_4 = obj->getMin();
 */