Teaching the Backtracking Method using Intelligent Games

Teaching programming techniques has always been a challenge. We exhibit an innovative way of teaching the backtracking programming strategy using educational games, in particular Sudoku. Compared to traditional ways of teaching backtracking, we used a new pseudocode that corresponds to the solution tree of the educational game. Most of the current textbooks present the traditional way to teach backtracking by showing the recursive call at the end of the backtrack() method. We will show an alternative to describing the backtrack() method by extending the solution with a choice, followed by the recursive call, which is in turn followed by an undo of that choice (that is, the backtracking step). As such, a path in the solution tree will correspond to a sequence of recursive calls of the backtrack() method. In this way, anyone who knows Sudoku rules or any other educational game (chess, eight queens, the knight’s tour problem, etc.) will most likely understand the backtracking strategy. Another contribution of our work is a mathematically sound method to transform a random Sudoku grid into a similar one which accepts only one Sudoku solution.