feat(convert-array): Add javascript solution for convert-array problem (blakeembrey#171)

Author: vasergen

solutions/javascript/convert-array.js

@@ -0,0 +1,26 @@
+'use strict';
+
+function getSwapIndex(currentInd, n) {
+  var swapInd = (currentInd % 3) * n + parseInt(currentInd/3);
+  while (swapInd < currentInd) {
+    swapInd = getSwapIndex(swapInd, n);
+  }
+
+  return swapInd;
+}
+
+function convert(arr) {
+  var n = parseInt(arr.length / 3);
+
+  for(var i = 0; i < arr.length; i++) {
+    var swapInd = getSwapIndex(i, n);
+
+    var tmp = arr[i];
+    arr[i] = arr[swapInd];
+    arr[swapInd] = tmp;
+  }
+
+  return arr;
+}
+
+module.exports = convert;

tests/javascript/convert-array.js

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+var assert    = require('assert');
+var convert = require('../../solutions/javascript/convert-array');
+
+describe('Convert Array', function() {
+  it('should convert an array', function() {
+    var arr = [
+      'a1', 'a2', 'a3', 'a4', 'a5',
+      'b1', 'b2', 'b3', 'b4', 'b5',
+      'c1', 'c2', 'c3', 'c4', 'c5'
+    ];
+
+    var expectedArr = [
+      'a1', 'b1', 'c1',
+      'a2', 'b2', 'c2',
+      'a3', 'b3', 'c3',
+      'a4', 'b4', 'c4',
+      'a5', 'b5', 'c5'
+    ];
+
+    convert(arr);
+
+    for(var i = 0; i < arr.length; i++) {
+        assert.equal(arr[i], expectedArr[i]);
+    }
+  })
+})