Merge pull request #252 from vish-han/patch-6

Rotate a Matrix by 90deg added

Author: SarthakKeshari

GeeksForGeeks/Rotate_Matrix_by_90deg.java

@@ -0,0 +1,39 @@
+//Question : you are given an 2D array , you have to rotate the Matrix bt 90deg and return it;
+
+public class ArrayPermutation {
+    public static void main(String[] args) {
+        int[][] array = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
+      //array before rotation
+        for (int i = 0; i < array.length; i++) {
+            for (int j = 0; j < array.length; j++) {
+                System.out.print(array[i][j] + " ");
+            }
+            System.out.println();
+        }
+rotate(array);
+        System.out.println("===========================================================");
+        System.out.println("after Rotation");
+
+        for (int i = 0; i < array.length; i++) {
+            for (int j = 0; j < array.length; j++) {
+                System.out.print(array[i][j] + " ");
+            }
+            System.out.println();
+        }
+    }
+
+//this functon will rotate the array by 90deg by taking transpose the array and rotate each row
+    static void rotate(int[][] matrix) {
+        int n = matrix.length;
+        for (int i = 0; i < (n + 1) / 2; i++) {
+            for (int j = 0; j < n / 2; j++) {
+                int temp = matrix[n - 1 - j][i];
+                matrix[n - 1 - j][i] = matrix[n - 1 - i][n - j - 1];
+                matrix[n - 1 - i][n - j - 1] = matrix[j][n - 1 - i];
+                matrix[j][n - 1 - i] = matrix[i][j];
+                matrix[i][j] = temp;
+            }
+        }
+    }
+
+}