MinStack.java

/**
 * Created by yasin_000 on 21.8.2017.
 */
public class MinStack {

 Node top;
 int size = 0;

 public void push(int x) {
 size++;
 if(top == null) {
 top = new Node(x);
 }
 else {
 Node temp = new Node(x);
 temp.next = top;
 temp.min = Math.min(top.min, x);
 top = temp;
 }
 }

 public void pop() {
 if(top == null) {
 System.out.println("Stack empty!");
 return;
 }

 top = top.next;
 size--;
 }

 public int top() {
 if(top == null) {
 System.out.println("Stack empty!");
 return Integer.MAX_VALUE;
 }

 return top.value;
 }

 public int min() {
 if(top == null) {
 System.out.println("Stack empty!");
 return Integer.MAX_VALUE;
 }
 return top.min;
 }

}

class Node {
 int value;
 int min;
 Node next;

 Node(int x) {
 value = x;
 next = null;
 min = x;
 }
}