Min Stack

1. Title

Min Stack

2. Http address

https://leetcode.com/problems/min-stack/

import java.util.*;
public class MinStack {

    // Accepted 
    public LinkedList<Integer> stack = new LinkedList<Integer>();
    public LinkedList<Integer> min_stack = new LinkedList<Integer>();
    
      public void push(int x) {
          
              stack.offerFirst(x);
              
              if ( min_stack.isEmpty() || x < min_stack.peekFirst()) {
                  min_stack.offerFirst(x);
              }else{
                  min_stack.offerFirst(min_stack.peekFirst());
              }
      }

     public void pop() {
            stack.pollFirst();
            min_stack.pollFirst();
     }

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

        public int getMin() {
                return min_stack.peekFirst();
        }
}

3. The question

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.

4. My code(AC)