MinStack.java

// Time Complexity : O(1)
// Space Complexity : O(1)
// Did this code successfully run on Leetcode : YES
// Any problem you faced while coding this : No


// Your code here along with comments explaining your approach

class MinStack {

    Stack<Integer> st;
    int min;
 
    public MinStack() {
        this.st= new Stack<>();
        this.min=Integer.MAX_VALUE;
        
    }
    
    public void push(int val) {
        if(min>=val)
        {
            st.push(min);
            min=val;
        }
        
        st.push(val);
        
    }
    
    public void pop() {

       if(min==st.pop()){
           min=st.pop();
       }
       
        
    }
    
    public int top() {
       return st.peek();
        
    }
    
    public int getMin() {
       return min;
    }
}

/**
 * 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();
 */