Add solution #48

Author: JoshCrozier

Diff for: README.md

@@ -43,6 +43,7 @@
 42|[Trapping Rain Water](./0042-trapping-rain-water.js)|Hard|
 43|[Multiply Strings](./0043-multiply-strings.js)|Medium|
 46|[Permutations](./0046-permutations.js)|Medium|
+48|[Rotate Image](./0048-rotate-image.js)|Medium|
 49|[Group Anagrams](./0049-group-anagrams.js)|Medium|
 50|[Pow(x, n)](./0050-powx-n.js)|Medium|
 53|[Maximum Subarray](./0053-maximum-subarray.js)|Easy|

Diff for: solutions/0048-rotate-image.js

@@ -0,0 +1,27 @@
+/**
+ * 48. Rotate Image
+ * https://leetcode.com/problems/rotate-image/
+ * Difficulty: Medium
+ *
+ * You are given an n x n 2D matrix representing an image, rotate the image by
+ * 90 degrees (clockwise).
+ *
+ * You have to rotate the image in-place, which means you have to modify the input
+ * 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.
+ */
+
+/**
+ * @param {number[][]} matrix
+ * @return {void} Do not return anything, modify matrix in-place instead.
+ */
+var rotate = function(matrix) {
+  matrix = matrix.reverse();
+
+  for (let i = 0; i < matrix.length; i++) {
+    for (let j = 0; j < i; j++) {
+      [matrix[i][j], matrix[j][i]] = [matrix[j][i], matrix[i][j]];
+    }
+  }
+
+  return matrix;
+};