Write a program to rotate a matrix.

Interview Questions and Answers

Q1. Write a program to rotate a matrix.

Ans. public class Matrix {

   public static void main(String[] args) {
      int[][] matrix = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
      };
      Matrix.rotateMatrix(matrix);
      for (int i = 0; i < matrix.length; i ){
         for (int j = 0; j < matrix.length; j ){
            System.out.print(matrix[i][j] " ");
         }
         System.out.println();
      }
   }

   public static void rotateMatrix(int[][] matrix){
      int row = matrix.length;
      //first find the transpose of the matrix.
      for (int i = 0; i < row; i ){
         for (int j = i; j < row; j ){
            int temp = matrix[i][j];
            matrix[i][j] = matrix[j][i];
            matrix[j][i] = temp;
         }
      }
      //reverse each row
      for (int i = 0; i< row; i ){
         for(int j = 0; j< row/2; j ){
            int temp = matrix[i][j];
            matrix[i][j] = matrix[i][row - 1 - j];
            matrix[i][row - 1 - j] = temp;
         }
      }

   }

}

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