From 4a17a23cc583a112a497df3cb8777351eccaa320 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Karabu=C5=82a-Stysiak?= <jakub.karabula@gmail.com>
Date: Tue, 2 Oct 2018 13:56:53 +0200
Subject: [PATCH] Add DFS and BFS algorithms

---
 graphs/bfs.js | 44 ++++++++++++++++++++++++++++++++++++++++++++
 graphs/dfs.js | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+)
 create mode 100644 graphs/bfs.js
 create mode 100644 graphs/dfs.js

diff --git a/graphs/bfs.js b/graphs/bfs.js
new file mode 100644
index 0000000..96f6348
--- /dev/null
+++ b/graphs/bfs.js
@@ -0,0 +1,44 @@
+/*
+  A non-recursive implementation of bfs with worst-case space complexity O(|E|)
+*/
+
+function Vertex (name, neighbours) {
+  this.name = name;
+  this.neighbours = neighbours;
+}
+
+function bfs (root) {
+  var visited = {}
+  var stack = []
+
+  stack.push(root)
+  while(!!stack.length) {
+    var vertex = stack.shift()
+
+    if (!visited[vertex.name]) {
+      visited[vertex.name] = true
+      console.log('Visiting vertex ', vertex.name)
+
+      var len = vertex.neighbours.length
+      for (var index = 0; index < len; index++) {
+        stack.push(vertex.neighbours[index])
+      }
+    }
+  }
+}
+
+var root = new Vertex('root', [
+  new Vertex('child 1', [
+    new Vertex('grandchild 1', []), new Vertex('grandchild 2', [])
+  ]),
+  new Vertex('child 2', [
+    new Vertex('grandchild 3', []),
+  ]),
+  new Vertex('child 3', [
+    new Vertex('grandchild 4', [
+      new Vertex('grandgrandchild 1', [])
+    ]),
+  ]),
+])
+
+bfs(root)
diff --git a/graphs/dfs.js b/graphs/dfs.js
new file mode 100644
index 0000000..bcbfe8e
--- /dev/null
+++ b/graphs/dfs.js
@@ -0,0 +1,46 @@
+/*
+  A non-recursive implementation of DFS with worst-case space complexity O(|E|)
+
+  according to wiki pseudocode https://en.wikipedia.org/wiki/Depth-first_search
+*/
+
+function Vertex (name, neighbours) {
+  this.name = name;
+  this.neighbours = neighbours;
+}
+
+function dfs (root) {
+  var visited = {}
+  var stack = []
+
+  stack.push(root)
+  while(!!stack.length) {
+    var vertex = stack.pop()
+
+    if (!visited[vertex.name]) {
+      visited[vertex.name] = true
+      console.log('Visiting vertex ', vertex.name)
+
+      var len = vertex.neighbours.length
+      for (var index = 0; index < len; index++) {
+        stack.push(vertex.neighbours[index])
+      }
+    }
+  }
+}
+
+var root = new Vertex('root', [
+  new Vertex('child 1', [
+    new Vertex('grandchild 1', []), new Vertex('grandchild 2', [])
+  ]),
+  new Vertex('child 2', [
+    new Vertex('grandchild 3', []),
+  ]),
+  new Vertex('child 3', [
+    new Vertex('grandchild 4', [
+      new Vertex('grandgrandchild 1', [])
+    ]),
+  ]),
+])
+
+dfs(root)