JavaAlgorithms/Others/RotateMatriceBy90Degree.java

package Others;

/**
 * Given a matrix of size n x n We have to rotate this matrix by 90 Degree Here is the algorithm for
 * this problem .
 */
import java.util.*;

class Rotate_by_90_degree {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int t = sc.nextInt();

    while (t-- > 0) {
      int n = sc.nextInt();
      int[][] arr = new int[n][n];

      for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) arr[i][j] = sc.nextInt();

      Rotate g = new Rotate();
      g.rotate(arr);
      printMatrix(arr);
    }
    sc.close();
  }

  static void printMatrix(int arr[][]) {
    for (int i = 0; i < arr.length; i++) {
      for (int j = 0; j < arr[0].length; j++) System.out.print(arr[i][j] + " ");
      System.out.println("");
    }
  }
}

/** Class containing the algo to roate matrix by 90 degree */
class Rotate {
  static void rotate(int a[][]) {
    int n = a.length;
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < n; j++) {
        if (i > j) {
          int temp = a[i][j];
          a[i][j] = a[j][i];
          a[j][i] = temp;
        }
      }
    }
    int i = 0, k = n - 1;
    while (i < k) {
      for (int j = 0; j < n; j++) {
        int temp = a[i][j];
        a[i][j] = a[k][j];
        a[k][j] = temp;
      }

      i++;
      k--;
    }
  }
}