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

04_quicksort/ES6/01_loop_sum.js

@@ -0,0 +1,9 @@
+const sum = (arr) => {
+  let total = 0;
+  for (let x = 0; x < arr.length; x += 1) {
+    total += arr[x];
+  }
+  return total;
+};
+
+console.log(sum([1, 2, 3, 4])); // 10

04_quicksort/ES6/02_recursive_sum.js

@@ -0,0 +1,8 @@
+const sum = (list) => {
+  if (list.length === 0) {
+    return 0;
+  }
+  return list[0] + sum(list.slice(1));
+};
+
+console.log(sum([1, 2, 3, 4])); // 10

04_quicksort/ES6/03_recursive_count.js

@@ -0,0 +1,8 @@
+const count = (list) => {
+  if (list.length === 0) {
+    return 0;
+  }
+  return 1 + count(list.slice(1));
+};
+
+console.log(count([0, 1, 2, 3, 4, 5])); // 6

04_quicksort/ES6/04_recursive-max.js

@@ -0,0 +1,9 @@
+const max = (list) => {
+  if (list.length === 2) {
+    return list[0] > list[1] ? list[0] : list[1];
+  }
+  const subMax = max(list.slice(1));
+  return list[0] > subMax ? list[0] : subMax;
+};
+
+console.log(max([1, 5, 10, 25, 16, 1])); // 25

04_quicksort/ES6/05_quicksort.js

@@ -0,0 +1,12 @@
+const quickSort = (array) => {
+  if (array.length < 2) {
+    return array;
+  }
+  const pivot = array[0];
+  const less = array.filter(item => item < pivot);
+  const greater = array.filter(item => item > pivot);
+
+  return [...quickSort(less), pivot, ...quickSort(greater)];
+};
+
+console.log(quickSort([10, 5, 2, 3])); // [2, 3, 5, 10]

04_quicksort/es6/quicksort.js

@@ -1,18 +0,0 @@
-const quickSort = (array) => {
-	if (array.length < 2) {
-		return array;
-	}
-	if (array.length === 2) {
-		// if first elem more than second will swap them and return it like new array.
-		return array[0] < array[1] ? array : [array[1], array[0]];
-	}
-
-	const pivot = array[0]
-	const itemsAreLessPivotSubArray = array.filter(item => item < pivot);
-	const itemsAreMoreThenPivotSubArray = array.filter(item => item > pivot);
-
-	return [...quickSort(itemsAreLessPivotSubArray), pivot, ...quickSort(itemsAreMoreThenPivotSubArray)];
-};
-
-module.exports = quickSort;
-console.log(quicksort([10, 5, 2, 3])); // [2, 3, 5, 10]