Fix for issue kunal-kushwaha#1388 - correcting isSafe method in sudoku solver.

Author: Akhil-Selukar

lectures/14-recursion/code/src/com/kunal/backtracking/SudokuSolver.java

@@ -80,7 +80,7 @@ static boolean isSafe(int[][] board, int row, int col, int num) {
         // check the row
         for (int i = 0; i < board.length; i++) {
             // check if the number is in the row
-            if (board[row][i] == num) {
+            if (board[i][col] == num) {
                 return false;
             }
         }