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MyStack.java
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MyStack.java
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public class MyStack<E> {
private Node<E> head;
private int size;
public MyStack() {
this.size = 0;
}
private static class Node<E> {
E value;
Node<E> next;
public Node(E value) {
this.value = value;
this.next = null;
}
}
public int size() {
return size;
}
public void push(E value) {
Node<E> newNode = new Node<E>(value);
newNode.next = head;
head = newNode;
size++;
}
public E peek() {
return head.value;
}
public E pop() {
if (size <= 0)
return null;
E value = head.value;
head = head.next;
size--;
return value;
}
public String toString() {
if (size == 0)
return "[ ]";
Node<E> node = head;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < size; i++) {
sb.append("[ ");
sb.append(node.value);
sb.append(" ]");
if (node.next != null) {
node = node.next;
sb.append(" --> ");
}
}
return sb.toString();
}
}