added answer for ch1_q7

Author: kloncentaur8

lib/data-structures/chapter-1/1_7.js

@@ -0,0 +1,25 @@
+module.exports = Strings_1_7 = (function() {
+  return {
+    // Rotates a matrix 90 degrees clockwise
+    // Solution #7 from the book.
+    // @param {Array} img - matrix
+    // @retuns {Boolean} - a rotated a matrix
+    rotateMatrix: function(img) {
+      var len = img.length - 1;
+      for (var i1 = 0; i1 < len; i1++) {
+        for (var i2 = i1; i2 < len - i1; i2++) {
+          var increasing = i2;
+          var decreasing = len - i2;
+          var fixedMax = len - i1;
+          var fixedMin = i1;
+          var tmp = img[decreasing][fixedMin]; //left
+          img[decreasing][fixedMin] = img[fixedMax][decreasing]; //bottom
+          img[fixedMax][decreasing] = img[increasing][fixedMax]; //right
+          img[increasing][fixedMax] = img[fixedMin][increasing]; // top
+          img[fixedMin][increasing] = tmp;
+        }
+      }
+      return img;
+    }
+  };
+}());

test/data-structures/chapter-1/1_7_Spec.js

@@ -0,0 +1,21 @@
+require('../../test_helper');
+describe('1.7 #rotateMatrix', function() {
+  it('returns a rotated matrix', function() {
+    var data = [
+        [
+            [1, 2, 3, 4, 5],
+            [6, 7, 8, 9, 10],
+            [11, 12, 13, 14, 15],
+            [16, 17, 18, 19, 20],
+            [21, 22, 23, 24, 25]
+        ], [
+            [21, 16, 11, 6, 1],
+            [22, 17, 12, 7, 2],
+            [23, 18, 13, 8, 3],
+            [24, 19, 14, 9, 4],
+            [25, 20, 15, 10, 5]
+        ]
+    ];
+    expect(Strings_1_7.rotateMatrix(data[0])).to.deep.equal(data[1]);
+  });
+});

test/data-structures/chapter-1/1_8_Spec.js

@@ -1,5 +1,5 @@
 require('../../test_helper');
-describe('1.9 #isRotation', function () {
+describe('1.8 #isRotation', function () {
   var str1, str2;
   beforeEach(function () {
     str1 = 'waterbottle';