Implemented simple graph (Closes CoffeelessProgrammer#8)

All core data structures are implemented and importable.

Author: CoffeelessProgrammer

Data-Structures/Graphs/SimpleGraph.ts

@@ -0,0 +1,87 @@
+type StrIndexedObject = { [index: string]: Set<string> };
+
+
+export default class SimpleGraph {
+  private numberOfNodes: number;
+  private adjacentList: StrIndexedObject;
+
+  constructor() {
+    this.numberOfNodes = 0;
+    this.adjacentList = Object.create({});
+  }
+
+  public getNodeCount(): number {
+    return this.numberOfNodes;
+  }
+
+  public addVertex(node: string) {
+    this.adjacentList[node] = new Set<string>();
+    ++this.numberOfNodes;
+  }
+
+  public addEdge(node1: string, node2: string) {
+    // Undirected, unweighted graph
+    this.adjacentList[node1].add(node2);
+    this.adjacentList[node2].add(node1);
+  }
+
+  public toString(): string {
+    const allNodes = Object.keys(this.adjacentList);
+
+    let representation: string = "";
+
+    for (let node of allNodes) {
+      let nodeConnections = this.adjacentList[node];
+      let vertex;
+      let count = 0;
+      let connections = " { ";
+      for (vertex of nodeConnections) {
+        connections += vertex + (count < nodeConnections.size-1 ? ", ": " ");
+        ++count;
+      }
+      representation += (node + "-->" + connections + '}\n');
+    }
+    return representation;
+  }
+}
+
+function printGraph(graph: SimpleGraph) {
+  console.log(graph.toString());
+}
+
+//---------------------------------------------------------------------
+// ----------                 MAIN PROGRAM                   ----------
+//---------------------------------------------------------------------
+if (import.meta.main) {
+
+  let simpleGraph = new SimpleGraph();
+
+  simpleGraph.addVertex("0");
+  simpleGraph.addVertex("1");
+  simpleGraph.addVertex("2");
+  simpleGraph.addVertex("3");
+  simpleGraph.addVertex("4");
+  simpleGraph.addVertex("5");
+  simpleGraph.addVertex("6");
+  simpleGraph.addEdge("3", "1");
+  simpleGraph.addEdge("3", "4");
+  simpleGraph.addEdge("4", "2");
+  simpleGraph.addEdge("4", "5");
+  simpleGraph.addEdge("1", "2");
+  simpleGraph.addEdge("1", "0");
+  simpleGraph.addEdge("0", "2");
+  simpleGraph.addEdge("6", "5");
+
+  printGraph(simpleGraph);
+
+  // RUN:   deno run Data-Structures/Graphs/Graph.ts
+}
+
+// --------------------------- Terminal Output: ---------------------------
+// 0--> { 1, 2 }
+// 1--> { 3, 2, 0 }
+// 2--> { 4, 1, 0 }
+// 3--> { 1, 4 }
+// 4--> { 3, 2, 5 }
+// 5--> { 4, 6 }
+// 6--> { 5 }

Data-Structures/README.md

@@ -13,7 +13,7 @@
   - Binary Heap
     - Priority Queue
   - Trie
-- [ ] Graphs
+- [X] Graphs
 
 ## Resources
 - [The Data Structures Handbook](https://www.thedshandbook.com/ "DS Handbook")
@@ -24,6 +24,10 @@
 - [Arrays vs Linked Lists: Youtube](https://youtu.be/DyG9S9nAlUM)
 - [Linked List: VisuAlgo](https://visualgo.net/en/list)
 
+### Graphs
+- [The Internet Map](https://internet-map.net/)
+- [Graphs: VisuAlgo](https://visualgo.net/en/graphds)
+
 ### Trees
 - [Binary Search Tree: VisuAlgo](https://visualgo.net/bn/bst?slide=1)
 - [Binary Heap: VisuAlgo](https://visualgo.net/en/heap)

README.md

@@ -14,7 +14,7 @@
 - [X] Queues
 - [X] Linked Lists
 - [X] Trees
-- [ ] Graphs
+- [X] Graphs
 
 ### Algorithms
 - [ ] Recursion