adding stack data structure

Author: mamenesia

stack/directions.md

@@ -0,0 +1,37 @@
+# --- Directions
+
+Create a stack data structure.  The stack
+should be a class with methods 'push', 'pop', and
+'peek'.  Adding an element to the stack should
+store it until it is removed.
+
+# --- Examples
+
+    const s = new Stack();
+    s.push(1);
+    s.push(2);
+    s.pop(); should returns 2
+    s.pop(); should returns 1
+
+
+# --- Solutions
+
+// Solution
+
+    class Stack {
+      constructor() {
+        this.data = [];
+      }
+
+      push(record) {
+        this.data.push(record);
+      }
+
+      pop() {
+        return this.data.pop();
+      }
+
+      peek() {
+        return this.data[this.data.length -1];
+      }
+    }

stack/stack.js

@@ -0,0 +1,34 @@
+// --- Directions
+
+// Create a stack data structure.  The stack
+// should be a class with methods 'push', 'pop', and
+// 'peek'.  Adding an element to the stack should
+// store it until it is removed.
+
+// --- Examples
+
+//   const s = new Stack();
+//   s.push(1);
+//   s.push(2);
+//   s.pop(); should returns 2
+//   s.pop(); should returns 1
+
+// Solution
+
+class Stack {
+  constructor() {
+    this.data = [];
+  }
+
+  push(record) {
+    this.data.push(record);
+  }
+
+  pop() {
+    return this.data.pop();
+  }
+
+  peek() {
+    return this.data[this.data.length -1];
+  }
+}