#### Rotate Matrix By 90 Degrees

d
```package com.thealgorithms.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.Scanner;

final class Rotate_by_90_degrees {
private Rotate_by_90_degrees() {
}

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.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
*/
final class Rotate {
private 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;
int 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--;
}
}
}
```