More comments.

solver/types.go

@@ -9,16 +9,28 @@ import (
 // Solve a given Sudoku puzzle by iterating through all possible solutions.
 type Solver struct {
 	Controller *controller.Controller
-	row1s      []int
-	row2s      []int
-	row3s      []int
-	row4s      []int
-	row5s      []int
-	row6s      []int
-	row7s      []int
-	row8s      []int
-	row9s      []int
-	Iter       int64
-	counter    atomic.Int64
-	rates      []int64
+	// Slice of possible blocks for the 1st row.
+	row1s []int
+	// Slice of possible blocks for the 2nd row.
+	row2s []int
+	// Slice of possible blocks for the 3rd row.
+	row3s []int
+	// Slice of possible blocks for the 4th row.
+	row4s []int
+	// Slice of possible blocks for the 5th row.
+	row5s []int
+	// Slice of possible blocks for the 6th row.
+	row6s []int
+	// Slice of possible blocks for the 7th row.
+	row7s []int
+	// Slice of possible blocks for the 8th row.
+	row8s []int
+	// Slice of possible blocks for the 9th row.
+	row9s []int
+	// Maximum number of possible solutions with the current set of rows.
+	Iter int64
+	// Progress counter, needs atomic due to the number of updates.
+	counter atomic.Int64
+	// Slice of rates for accurate duration estimation.
+	rates []int64
 }