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

09_dynamic_programming/ES6/01_longest_common_subsequence.js

@@ -0,0 +1,7 @@
+if (word_a[i] === word_b[j]) {
+  // The letters match
+  cell[i][j] = cell[i - 1][j - 1] + 1;
+} else {
+  // The letters don't match
+  cell[i][j] = Math.max(cell[i - 1][j], cell[i][j - 1]);
+}

09_dynamic_programming/ES6/examples/base.js

@@ -0,0 +1,9 @@
+const initializeMatrix = (rows, cols) => {
+  const matrix = [];
+  for (let i = 0; i < rows.length; i += 1) {
+    matrix.push(Array(cols.length).fill(0));
+  }
+  return matrix;
+};
+
+export default initializeMatrix;

09_dynamic_programming/ES6/examples/diff_two_words.js

@@ -0,0 +1,27 @@
+import base from './base';
+
+const diff = (firstWord, secondWord) => {
+  const arr1 = firstWord.split('');
+  const arr2 = secondWord.split('');
+  const matrix = initializeMatrix(arr1, arr2);
+  for (let i = 0; i < arr1.length; i += 1) {
+    for (let j = 0; j < arr2.length; j += 1) {
+      if (arr1[i] === arr2[j]) {
+        if (i > 0 && j > 0) {
+          matrix[i][j] = matrix[i - 1][j - 1] + 1;
+        } else {
+          matrix[i][j] = 1;
+        }
+      } else {
+        if (i > 0 && j > 0) {
+          matrix[i][j] = Math.max(matrix[i - 1][j], matrix[i][j - 1]);
+        } else {
+          matrix[i][j] = 0;
+        }
+      }
+    }
+  }
+  return matrix[arr1.length - 1][arr2.length - 1];
+};
+
+export default diff;