Add square matrix rotation in-place algorithm.

src/algorithms/uncategorized/square-matrix-rotation/squareMatrixRotation.js

@@ -0,0 +1,28 @@
+/**
+ * @param {*[][]} originalMatrix
+ * @return {*[][]}
+ */
+export default function squareMatrixRotation(originalMatrix) {
+  const matrix = originalMatrix.slice();
+
+  // Do top-right/bottom-left diagonal reflection of the matrix.
+  for (let rowIndex = 0; rowIndex < matrix.length; rowIndex += 1) {
+    for (let columnIndex = rowIndex + 1; columnIndex < matrix.length; columnIndex += 1) {
+      const tmp = matrix[columnIndex][rowIndex];
+      matrix[columnIndex][rowIndex] = matrix[rowIndex][columnIndex];
+      matrix[rowIndex][columnIndex] = tmp;
+    }
+  }
+
+  // Do horizontal reflection of the matrix.
+  for (let rowIndex = 0; rowIndex < matrix.length; rowIndex += 1) {
+    for (let columnIndex = 0; columnIndex < matrix.length / 2; columnIndex += 1) {
+      const mirrorColumnIndex = matrix.length - columnIndex - 1;
+      const tmp = matrix[rowIndex][mirrorColumnIndex];
+      matrix[rowIndex][mirrorColumnIndex] = matrix[rowIndex][columnIndex];
+      matrix[rowIndex][columnIndex] = tmp;
+    }
+  }
+
+  return matrix;
+}