GH-174: Priority Queue (Heap) in C++

README.md

@@ -95,6 +95,12 @@ A data structure is a data organization, management, and storage format that is
 </td>
 </tr>
 <tr>
+<td>Priority Queue (Heap)</td>
+<td>
+<a href="/concepts/cpp/priority_queue.md"><code>cpp🐀</code></a>
+</td>
+</tr>
+<tr>
 <td colspan="2" align="center"><b>Algorithms</b></td>
 </tr>
 <tr>

concepts/cpp/labs/priority_queue.ipynb

@@ -0,0 +1,220 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Priority Queue \n",
+    "\n",
+    "A priority queue is a container that provides constant time lookup of the largest (by default) element, at the expense of logarithmic insertion and extraction.\n",
+    "\n",
+    "Real world examples of priority queues include:\n",
+    "\n",
+    "- The task queue in an operating system\n",
+    "- The call queue in a call center\n",
+    "- The list of pending requests at a web server, sorted by their priority\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Baisc usage of priority queue\n",
+    "\n",
+    "C++ has built-in object [`priority_queue`](https://cplusplus.com/reference/queue/priority_queue/) in `queue` library."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "vscode": {
+     "languageId": "cpp"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "#include <queue>\n",
+    "#include <vector>\n",
+    "#include <iostream>\n",
+    "\n",
+    "using namespace std;"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {
+    "vscode": {
+     "languageId": "cpp"
+    }
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "5\n",
+      "3\n",
+      "1\n"
+     ]
+    }
+   ],
+   "source": [
+    "priority_queue<int> pq;\n",
+    "\n",
+    "pq.push(1);\n",
+    "pq.push(5);\n",
+    "pq.push(3);\n",
+    "\n",
+    "while (!pq.empty()) {\n",
+    "    cout << pq.top() << endl;\n",
+    "    pq.pop();\n",
+    "}"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Min priority queue\n",
+    "\n",
+    "If you want min priority queue, you can use `greater<int>` as the third argument."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {
+    "vscode": {
+     "languageId": "cpp"
+    }
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "1\n",
+      "3\n",
+      "5\n"
+     ]
+    }
+   ],
+   "source": [
+    "priority_queue<int, vector<int>, greater<int>> pq;\n",
+    "\n",
+    "pq.push(1);\n",
+    "pq.push(5);\n",
+    "pq.push(3);\n",
+    "\n",
+    "while (!pq.empty()) {\n",
+    "    cout << pq.top() << endl;\n",
+    "    pq.pop();\n",
+    "}"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Priority queue with custom comparator\n",
+    "\n",
+    "Custom Comparision with `priority_queue` is a little bit interesting. You can use custom struct as the third argument."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {
+    "vscode": {
+     "languageId": "cpp"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "struct Node {\n",
+    "  int val;\n",
+    "  int priority;\n",
+    "};\n",
+    "\n",
+    "struct compare{\n",
+    "  public:\n",
+    "  bool operator()(Node& a,Node& b)\n",
+    "  {\n",
+    "      return a.priority < b.priority;\n",
+    "  }\n",
+    "};"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "metadata": {
+    "vscode": {
+     "languageId": "cpp"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "priority_queue<Node, vector<Node>, compare> pq;\n",
+    "pq.push({1, 2});\n",
+    "pq.push({5, 6});\n",
+    "pq.push({10, 3});"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 17,
+   "metadata": {
+    "vscode": {
+     "languageId": "cpp"
+    }
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "5, 6\n",
+      "10, 3\n",
+      "1, 2\n"
+     ]
+    }
+   ],
+   "source": [
+    "while(!pq.empty()){\n",
+    "    Node tmp = pq.top();\n",
+    "    cout << tmp.val << \", \" << tmp.priority << endl;\n",
+    "    pq.pop();\n",
+    "}"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## References\n",
+    "\n",
+    "* [Declaring a priority_queue in c++ with a custom comparator](https://stackoverflow.com/questions/16111337/declaring-a-priority-queue-in-c-with-a-custom-comparator)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "C++17",
+   "language": "C++17",
+   "name": "xcpp17"
+  },
+  "language_info": {
+   "codemirror_mode": "text/x-c++src",
+   "file_extension": ".cpp",
+   "mimetype": "text/x-c++src",
+   "name": "c++",
+   "version": "17"
+  },
+  "orig_nbformat": 4
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}

concepts/cpp/priority_queue.md

@@ -0,0 +1,63 @@
+# Priority Queue
+
+<a href="https://github.com/rain1024/datastructures-algorithms-competitive-programming/blob/main/concepts/cpp/labs/priority_queue.ipynb">
+<img src="https://img.shields.io/badge/🧪-notebook-brightgreen">
+</a>
+
+A priority queue is an abstract data type that allows the storage of elements with priority. The elements are stored in such a way that the element with the highest priority is always at the front of the queue, and the element with the lowest priority is at the back of the queue.
+
+![](../abstract/data-structures/priority_queue.png)
+
+
+## 🎨 Priority Queue Design
+
+**Methods**
+
+|                | Definition                                                  |
+|----------------|-------------------------------------------------------------|
+| enqueue        | Add element to the queue                                    |
+| dequeue        | remove the element with the highest priority from the queue |
+
+
+## 💻 Priority Queue Implementation in C++
+
+C++ has built-in object [`priority_queue`](https://cplusplus.com/reference/queue/priority_queue/) in `queue` library.
+
+```cpp
+#include <iostream>
+#include <queue>
+
+int main(){
+  priority_queue<int> pq;
+
+  pq.push(1);
+  pq.push(5);
+  pq.push(3);
+
+  while (!pq.empty()) {
+      cout << pq.top() << endl;
+      pq.pop();
+  }
+
+  return 0;
+}
+
+```
+
+## 📈 Complexity Analysis of Priority Queue
+
+
+| Operation       | Complexity          |
+|-----------------|---------------------|
+| push            | $O(log N)$          |
+| pop             | $O(log N)$          |
+| top             | $O(1)$              |
+
+## 🔗 Further Reading
+
+* [Priority Queue (data structures)](https://en.wikipedia.org/wiki/Priority_queue), wikipedia
+* ▶️ [Priority Queue (1/5) Introduction](https://www.youtube.com/watch?v=wptevk0bshY&ab_channel=WilliamFiset), WilliamFiset, 2017
+* ▶️ [Priority Queue (2/5) Min Heaps and Max Heaps](https://www.youtube.com/watch?v=HCEr35qpawQ&ab_channel=WilliamFiset), WilliamFiset, 2017
+* ▶️ [Priority Queue (3/5) Inserting Elements](https://www.youtube.com/watch?v=QOJ-CmQiXko&list=PLDV1Zeh2NRsB6SWUrDFW2RmDotAfPbeHu&index=16&ab_channel=WilliamFiset), WilliamFiset, 2017
+* ▶️ [Priority Queue (4/5) Removing Elements](https://www.youtube.com/watch?v=eVq8CmoC1x8&list=PLDV1Zeh2NRsB6SWUrDFW2RmDotAfPbeHu&index=17&ab_channel=WilliamFiset), WilliamFiset, 2017
+* ▶️ [Priority Queue (5/5) Code](https://www.youtube.com/watch?v=GLIRnUhknP0&list=PLDV1Zeh2NRsB6SWUrDFW2RmDotAfPbeHu&index=18&ab_channel=WilliamFiset), WilliamFiset, 2017

concepts/cpp/tree.md

@@ -72,7 +72,7 @@ int main()
 }
 ```
 
-## 📈 Complexity Analysis of [Awesome Type]
+## 📈 Complexity Analysis of Tree
 
 
 | Operation       | Complexity          |