Monday 31 August 2015

Rotate 2-D matrix by 90

Given N*M matrix, rotate it by 90 degree right

package core.geeks;
class Rotate90Degree {
      
       private static void rotateMatrix(int[][] array) {
              int oRow = array.length;
              int oCol = array[0].length;
              int[][] tArr = new int[oCol][oRow];

              int tCol = 3;
              for (int i = 0; i < oRow; i++){
                     for(int j = 0;  j < oCol; j++){
                           tArr[j][tCol] = array[i][j];
                     }
                     tCol--;
              }

              printGrid(tArr);
       }
      
       public static void main(String args[] ) throws Exception {
              int[][] array = {  {0, 1, 2, 3, 4},
                           {5, 6, 7, 8, 9},
                           {10, 11, 12, 13, 14},
                           {15, 16, 17, 18, 19}};
              rotateMatrix(array);
       }

       public static void printGrid(int[][] a) {
              for(int i = 0; i < a.length; i++) {
                     for(int j = 0; j < a[i].length; j++) {
                           System.out.printf("%5d ", a[i][j]);
                     }
                     System.out.println();
              }
       }
}

Output:
   15    10     5     0
   16    11     6     1
   17    12     7     2
   18    13     8     3
   19    14     9     4


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