chore: add some notes

.idea/.idea.EndMove.Sudoku.Solver/.idea/encodings.xml

@@ -1,4 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="Encoding" addBOMForNewFiles="with BOM under Windows, with no BOM otherwise" />
-</project>

EndMove.Sudoku.Solver.sln

@@ -1,4 +1,4 @@
-
+
 Microsoft Visual Studio Solution File, Format Version 12.00
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{67AA5CD2-BE13-4741-8F70-4FE3638271E4}"
 EndProject

src/EndMove.Sudoku.Solver.Core/Algorithms/BackTrackingSolver.cs

@@ -1,9 +1,15 @@
-namespace EndMove.Sudoku.Solver.Core.Algorithms;
+namespace EndMove.Sudoku.Solver.Core.Algorithms;
 
 public class BackTrackingSolver : SolverBase
 {
     public BackTrackingSolver(Action<int[,]> displayBoard) : base(displayBoard) { }
 
+    /**
+     * note for future me :
+     * - Maybe pre-process the board to get the empty cells and already know used values per row, col and box
+     * - Maybe keep a track of the current index to avoid searching for the next empty cell in the all 2d array
+     * - Maybe avoid using negation
+     */
     public override (bool, int[,]) Solve(int[,] board)
     {
         int row = -1, col = -1;

src/EndMove.Sudoku.Solver.Core/Program.cs

@@ -58,7 +58,9 @@ namespace EndMove.Sudoku.Solver.Core
 
             SudokuUtils.TwoDTo1D(store[0], out int[] sudoku1D);
             SudokuUtils.DisplayBoard(sudoku1D);
+            // TODO improve 2D backtracking solver
             // TODO 1D solver with backtracking
+            // TODO Add time measurement
 
             ISolver solver = new BackTrackingSolver(SudokuUtils.DisplayBoard);
             var (status, lol) = solver.Solve(store[0]);