Exemple #1
0
// solveByGuessing selects the position with minimum possibilities out of the remaining empty positions.
// For each of the possible values, the grid is solved. For each conflict, the state is backtracked.
// If no conflict is there, then recursively solveByGuessing on the remaining empty positions.
// Prints the solution, if found. Also increments the number of solutions.
func solveByGuessing(grid *datatypes.Grid, positions map[datatypes.Position]bool, iteration int) {
	// if all positions have been filled, then return
	if len(positions) == 0 {
		numSolutions++
		grid.Print()
		return
	}
	// copy remaining positions to next iteration, and start guessing for the position with minimum possibilities.
	pos := copyValuesForNextIteration(grid, positions, iteration)
	existingValue := grid[pos.X][pos.Y].IterationValues[iteration]
	for val := range existingValue.Possible {
		// update the cell with val for next iteration
		nextValue := grid[pos.X][pos.Y].IterationValues[iteration+1]
		*grid[pos.X][pos.Y].Val = val
		*nextValue.Val = val
		for key := range nextValue.Possible {
			if key != val {
				delete(nextValue.Possible, key)
			}
		}
		// start solving using the set value.
		if !eliminateUsingGivenValues(grid, iteration+1, pos.X, pos.Y, val) {
			// if no conflict, then call solveByGuessing for remaining positions.
			updatedPositions := remainingPositions(grid, positions)
			solveByGuessing(grid, updatedPositions, iteration+1)
		}
		// backtrack to previous state
		copyValuesForNextIteration(grid, positions, iteration)
	}
	return
}
Exemple #2
0
// setInput creates the initial grid for testing.
func setInput(grid *datatypes.Grid) int {
	setValue(grid, 0, 4, 4)
	setValue(grid, 0, 5, 5)

	setValue(grid, 1, 0, 8)
	setValue(grid, 1, 6, 2)
	setValue(grid, 1, 8, 7)

	setValue(grid, 2, 2, 2)
	setValue(grid, 2, 8, 4)

	setValue(grid, 3, 2, 6)
	setValue(grid, 3, 6, 3)
	setValue(grid, 3, 8, 2)

	setValue(grid, 4, 3, 1)

	setValue(grid, 5, 0, 2)
	setValue(grid, 5, 2, 7)
	setValue(grid, 5, 3, 4)
	setValue(grid, 5, 6, 6)

	setValue(grid, 6, 0, 6)
	setValue(grid, 6, 1, 4)
	setValue(grid, 6, 4, 9)
	setValue(grid, 6, 5, 8)

	setValue(grid, 7, 0, 7)
	setValue(grid, 7, 1, 9)
	setValue(grid, 7, 5, 4)

	setValue(grid, 8, 7, 3)

	grid.Print()
	return 23
}