[stack] Feat: 스택 구현

Author: hsik0225

ever/.idea/.gitignore

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
+

ever/.idea/description.html

@@ -0,0 +1,19 @@
+package com.codesquad;
+
+public class Main {
+
+    public static void main(String[] args) {
+        Stack<Integer> s = new Stack<Integer>();
+        s.push(1);
+        s.push(2);
+        s.push(3);
+        s.push(4);
+        System.out.println(s.pop());
+        System.out.println(s.pop());
+        System.out.println(s.peek());
+        System.out.println(s.pop());
+        System.out.println(s.isEmpty());
+        System.out.println(s.pop());
+        System.out.println(s.isEmpty());
+    }
+}

ever/.idea/encodings.xml

@@ -0,0 +1,44 @@
+package com.codesquad;
+
+import java.util.EmptyStackException;
+
+public class Stack<T> {
+
+    private Node<T> top;
+
+    public class Node<T> {
+        public T data;
+        public Node<T> next;
+
+        public Node(T data, Node<T> next) {
+            this.data = data;
+            this.next = next;
+        }
+    }
+
+    public T pop() {
+        if (this.top == null) {
+            throw new EmptyStackException();
+        }
+
+        T data = this.top.data;
+        this.top = this.top.next;
+        return data;
+    }
+
+    public T peek() {
+        if (top == null) {
+            throw new EmptyStackException();
+        }
+
+        return this.top.data;
+    }
+
+    public void push(T data) {
+        this.top = new Node<>(data, top);
+    }
+
+    public boolean isEmpty() {
+        return this.top == null;
+    }
+}