Add ES6 Examples to all chapters (#38)

* add ES6 example for binary search

* add ES6 example for selection sort

* add ES6 example for countdown

* add ES6 example for greet

* add ES6 example for factorial

* edit ES6 example for quicksort

* add ES6 example for loop sum

* add ES6 example for recursive sum

* add ES6 example for recursive count

* add ES6 example for recursive max

* add ES6 example for price of groceries

* add ES6 example for check voter

* add ES6 example for breadth-first search

* add ES6 example for dijkstras algorithm

* edit ES6 example for dijkstras algorithm

* edit ES6 example for set covering

* add ES6 example for longest common subsequence

06_breadth-first_search/ES6/01_breadth-first_search.js

@@ -0,0 +1,34 @@
+const personIsSeller = name => name[name.length - 1] === 'm';
+
+const graph = {};
+graph.you = ['alice', 'bob', 'claire'];
+graph.bob = ['anuj', 'peggy'];
+graph.alice = ['peggy'];
+graph.claire = ['thom', 'jonny'];
+graph.anuj = [];
+graph.peggy = [];
+graph.thom = [];
+graph.jonny = [];
+
+const search = (name) => {
+  let searchQueue = [];
+  searchQueue = searchQueue.concat(graph[name]);
+  // This array is how you keep track of which people you've searched before.
+  const searched = [];
+  while (searchQueue.length) {
+    const person = searchQueue.shift();
+    // Only search this person if you haven't already searched them
+    if (searched.indexOf(person) === -1) {
+      if (personIsSeller(person)) {
+        console.log(`${person} is a mango seller!`);
+        return true;
+      }
+      searchQueue = searchQueue.concat(graph[person]);
+      // Marks this person as searched
+      searched.push(person);
+    }
+  }
+  return false;
+};
+
+search('you'); // thom is a mango seller!