Add circular array code

solutions/object_oriented_design/circular_array/circular_array.ipynb

@@ -0,0 +1,186 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "This notebook was prepared by [Abhijeet Antin](https://github.com/abhijeet14antin). Source and license info is on [GitHub](https://github.com/donnemartin/system-design-primer)."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Design a circular array"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {
+    "jp-MarkdownHeadingCollapsed": true
+   },
+   "source": [
+    "## Constraints and assumptions\n",
+    "\n",
+    "* What are we queueing?\n",
+    "    * We are queueing integers\n",
+    "* Can we assume inputs are valid or do we have to validate them?\n",
+    "    * Assume they're valid\n",
+    "* Can we assume this fits memory?\n",
+    "    * Yes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Solution"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false,
+    "jupyter": {
+     "outputs_hidden": false
+    }
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Overwriting circular_array.py\n"
+     ]
+    }
+   ],
+   "source": [
+    "%%writefile circular_array.py\n",
+    "\n",
+    "class CircularArray(object):\n",
+    "\n",
+    "    def __init__(self, MAX_SIZE):\n",
+    "        self.MAX_SIZE = MAX_SIZE\n",
+    "        self.size = 0\n",
+    "        self.array = [None] * MAX_SIZE\n",
+    "        self.front = 0\n",
+    "        self.back = 0\n",
+    "\n",
+    "    def push(self, value):\n",
+    "        \"\"\"Push the value to the back of the circular array\n",
+    "        \"\"\"\n",
+    "        if self.size == self.MAX_SIZE:\n",
+    "            raise IndexError('Array is full')\n",
+    "        self.array[self.back] = value\n",
+    "        self.back += 1\n",
+    "        self.size += 1\n",
+    "        \n",
+    "        # wrap around\n",
+    "        if self.back == self.MAX_SIZE:\n",
+    "            self.back = 0\n",
+    "\n",
+    "    def pop(self):\n",
+    "        \"\"\"Pop a value from the front of the circular array\n",
+    "        \"\"\"\n",
+    "        if self.size == 0:\n",
+    "            raise IndexError('Array is empty')\n",
+    "        ret = self.array[self.front]\n",
+    "        self.front += 1\n",
+    "        self.size -= 1\n",
+    "\n",
+    "        # wrap around\n",
+    "        if self.front == self.MAX_SIZE:\n",
+    "            self.front = 0\n",
+    "        return ret\n",
+    "        \n",
+    "    def print_array(self):\n",
+    "        print('Array: ', end = ' ')\n",
+    "        if self.size == 0:\n",
+    "            print('empty')\n",
+    "            return\n",
+    "        i = self.front\n",
+    "        while True:\n",
+    "            print(self.array[i], end = ' ')\n",
+    "            i += 1\n",
+    "            if i == self.MAX_SIZE:\n",
+    "                i = 0\n",
+    "            if i == self.back:\n",
+    "                print()\n",
+    "                break\n",
+    "\n",
+    "    "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Array:  empty\n",
+      "Array:  1 2 3 4 5 \n",
+      "Array:  3 4 5 \n",
+      "Array:  3 4 5 6 \n"
+     ]
+    }
+   ],
+   "source": [
+    "from circular_array import CircularArray\n",
+    "ca = CircularArray(5)\n",
+    "ca.print_array()\n",
+    "ca.push(1)\n",
+    "ca.push(2)\n",
+    "ca.push(3)\n",
+    "ca.push(4)\n",
+    "ca.push(5)\n",
+    "ca.print_array()\n",
+    "\n",
+    "ca.pop()\n",
+    "ca.pop()\n",
+    "ca.print_array()\n",
+    "\n",
+    "ca.push(6)\n",
+    "ca.print_array()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.12.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}

solutions/object_oriented_design/circular_array/circular_array.py

@@ -0,0 +1,53 @@
+
+class CircularArray(object):
+
+    def __init__(self, MAX_SIZE):
+        self.MAX_SIZE = MAX_SIZE
+        self.size = 0
+        self.array = [None] * MAX_SIZE
+        self.front = 0
+        self.back = 0
+
+    def push(self, value):
+        """Push the value to the back of the circular array
+        """
+        if self.size == self.MAX_SIZE:
+            raise IndexError('Array is full')
+        self.array[self.back] = value
+        self.back += 1
+        self.size += 1
+        
+        # wrap around
+        if self.back == self.MAX_SIZE:
+            self.back = 0
+
+    def pop(self):
+        """Pop a value from the front of the circular array
+        """
+        if self.size == 0:
+            raise IndexError('Array is empty')
+        ret = self.array[self.front]
+        self.front += 1
+        self.size -= 1
+
+        # wrap around
+        if self.front == self.MAX_SIZE:
+            self.front = 0
+        return ret
+        
+    def print_array(self):
+        print('Array: ', end = ' ')
+        if self.size == 0:
+            print('empty')
+            return
+        i = self.front
+        while True:
+            print(self.array[i], end = ' ')
+            i += 1
+            if i == self.MAX_SIZE:
+                i = 0
+            if i == self.back:
+                print()
+                break
+
+