Update the README.md

README.md

@@ -15,13 +15,17 @@ I wrote [a blog post](https://blog.ligthert.net/posts/exploration-fun-and-proces
 * Split workloads among several computers
 
 ## Usage
-To use the sudoku solver, run the binary with all the parameters available:
+To use the sudoku solver, run the binary with all the `-row` parameters available. Use other parameters to tune our output or CPU usage.
 ```
 Usage of ./sudoku-funpark:
   -numcpu int
     	Number of CPU cores to assign to this task. (default 12)
+  -output string
+    	Type of output. 'human' for human readable. 'flat' for flat as stored in memory output. 'json' for JSON output. (default "human")
   -part int
     	Process part x in n parts. Cannot be lower than 1, or higher than specified in split. (default 1)
+  -print string
+    	'short': normal output;'long': normal output with timestamps; 'silent': Only print the results; (default "short")
   -row1 string
     	1st row of the sudoku puzzle. (default "000000000")
   -row2 string
@@ -50,7 +54,7 @@ Instead of using the 3x3 blocks with 3x3 digits, it uses horizontal rows from to
 ## Example
 To see the solver in action, run the tool with the following parameters.
 
-For a short running (~15 seconds) example:
+For a short running (~14 seconds) example:
 > $ ./sudoku-funpark -row1 769104802 -row2 154800060 -row3 832700154 -row4 600900328 -row5 045328670 -row6 328670945 -row7 597410280 -row8 006283090 -row9 200590006
 
 For a long running (~1 hours 15 minutes) example:
@@ -58,40 +62,40 @@ For a long running (~1 hours 15 minutes) example:
 
 The outpot (of the short running parameters) will look something like this:
 ```
-./sudoku-funpark -row1 769104802 -row2 154800060 -row3 832700154 -row4 600900328 -row5 045328670 -row6 328670945 -row7 597410280 -row8 006283090 -row9 200590006
-2025/01/24 00:05:58 Loading blocks
-2025/01/24 00:05:58 Loaded blocks (34.587221ms)
-2025/01/24 00:05:58 Populating blocks
-2025/01/24 00:05:58 Populated blocks (438.73054ms)
-2025/01/24 00:05:58 Number of (potential) solutions: 26542080
-2025/01/24 00:05:58 Validating solutions
-2025/01/24 00:05:59 Processing: 6% (1729332/26542080); Rate (avg): 1729330/sec for 1.000003166s; Time left (est.): 14 seconds
-2025/01/24 00:06:00 Processing: 13% (3461753/26542080); Rate (avg): 1732418/sec for 1.000002285s; Time left (est.): 13 seconds
-2025/01/24 00:06:01 Processing: 19% (5228965/26542080); Rate (avg): 1767215/sec for 1.000019297s; Time left (est.): 12 seconds
-2025/01/24 00:06:02 Processing: 26% (6996958/26542080); Rate (avg): 1767992/sec for 1.000200176s; Time left (est.): 11 seconds
-2025/01/24 00:06:03 Processing: 33% (8767450/26542080); Rate (avg): 1770495/sec for 1.000016352s; Time left (est.): 10 seconds
-2025/01/24 00:06:04 Processing: 39% (10576900/26542080); Rate (avg): 1809450/sec for 1.000014638s; Time left (est.): 8 seconds
-2025/01/24 00:06:05 Processing: 46% (12400058/26542080); Rate (avg): 1823158/sec for 1.000352862s; Time left (est.): 7 seconds
-2025/01/24 00:06:06 Processing: 53% (14185155/26542080); Rate (avg): 1785095/sec for 1.000254888s; Time left (est.): 6 seconds
-2025/01/24 00:06:07 Processing: 60% (15968402/26542080); Rate (avg): 1783245/sec for 1.000002305s; Time left (est.): 5 seconds
-2025/01/24 00:06:08 Processing: 66% (17655770/26542080); Rate (avg): 1687370/sec for 1.000068309s; Time left (est.): 5 seconds
-2025/01/24 00:06:09 Processing: 73% (19442885/26542080); Rate (avg): 1787111/sec for 1.000006984s; Time left (est.): 3 seconds
-2025/01/24 00:06:10 Processing: 79% (21183545/26542080); Rate (avg): 1740661/sec for 1.000002395s; Time left (est.): 3 seconds
-2025/01/24 00:06:11 Processing: 86% (22998945/26542080); Rate (avg): 1815402/sec for 1.000113534s; Time left (est.): 1 second
-2025/01/24 00:06:12 Processing: 90% (24109203/26542080); Rate (avg): 1110261/sec for 1.000312346s; Time left (est.): 2 seconds
-2025/01/24 00:06:13 Processing: 100% (26542080/26542080); Rate (avg): 0/sec for 1.000117421s; Time left (est.): N/A
-2025/01/24 00:06:13 Validated solutions (15.002654066s)
-2025/01/24 00:06:13
+./sudoku-funpark -row1 769104802 -row2 154800060 -row3 832700154 -row4 600900328 -row5 045328670 -row6 328670945 -row7 597410280 -row8 006283090 -row9 200590006 
+Loading blocks... Done! (38.957376ms)
+Populating blocks... Done! (92.087174ms)
+Number of (potential) solutions: 26542080
+Validating solutions
+Processing: 8% (2131893/26542080); Rate: 2131884/sec for 1.000028115s; Time left (est.): 11s
+Processing: 16% (4292163/26542080); Rate: 2160219/sec for 1.000087826s; Time left (est.): 10s
+Processing: 24% (6438334/26542080); Rate: 2146157/sec for 1.000017364s; Time left (est.): 9s
+Processing: 32% (8529362/26542080); Rate: 2090965/sec for 1.000367121s; Time left (est.): 8s
+Processing: 40% (10737065/26542080); Rate: 2207530/sec for 1.000072427s; Time left (est.): 7s
+Processing: 48% (12958905/26542080); Rate: 2221755/sec for 1.000003187s; Time left (est.): 6s
+Processing: 57% (15163877/26542080); Rate: 2204929/sec for 1.000002717s; Time left (est.): 5s
+Processing: 65% (17254760/26542080); Rate: 2090742/sec for 1.00008452s; Time left (est.): 4s
+Processing: 73% (19513142/26542080); Rate: 2258348/sec for 1.000071076s; Time left (est.): 3s
+Processing: 82% (21795213/26542080); Rate: 2282028/sec for 1.000076024s; Time left (est.): 2s
+Processing: 90% (24048891/26542080); Rate: 2253645/sec for 1.000146957s; Time left (est.): 1s
+Processing: 98% (26226252/26542080); Rate: 2177215/sec for 1.000129955s; Time left (est.): 0s
+Processing: 100% (26542080/26542080); Rate: 315792/sec for 1.000105149s; Time left (est.): 0s
+Validated solutions (13.001683829s)
+
 Solution #1:
-769154832
-154832769
-832769154
-671945328
-945328671
-328671945
-597416283
-416283597
-283597416
+╔═══════════╗
+║769│154│832╢
+║154│832│769╢
+║832│769│154╢
+╟───┼───┼───╢
+║671│945│328╢
+║945│328│671╢
+║328│671│945╢
+╟───┼───┼───╢
+║597│416│283╢
+║416│283│597╢
+║283│597│416╢
+╚═══════════╝
 ```
 
 ## Caveats

controller/types.go

@@ -1,5 +1,7 @@
 package controller
 
+import "gitea.ligthert.net/golang/sudoku-funpark/outputter"
+
 // Simple interface to store values shared amongst packages.
 type Controller struct {
 	// All possible blocks/rows available
@@ -32,4 +34,8 @@ type Controller struct {
 	Part int
 	// Type of output requested
 	Output string
+	// Select printing method
+	Print string
+	// Outputter package
+	Outputter *outputter.Outputter
 }

export/Export.go

@@ -0,0 +1,14 @@
+package export
+
+func (export *Export) Export() (render string) {
+	// Print the valid solutions
+	switch export.Controller.Output {
+	case "human":
+		render = export.renderHumanReadable()
+	case "flat":
+		render = export.renderFlat()
+	case "json":
+		render = export.renderJSON()
+	}
+	return
+}

export/PrintFlatSolutions.go

@@ -1,14 +0,0 @@
-package export
-
-import (
-	"fmt"
-	"log"
-)
-
-// Print solutions into a human friendly format for in the console.
-func (export *Export) PrintFlatSolutions() {
-	for solutionIndex, solution := range export.Controller.Solutions {
-		log.Printf("\nSolution #%d:", solutionIndex+1)
-		fmt.Println(solution)
-	}
-}

export/PrintHumanReadableSolutions.go

@@ -1,21 +0,0 @@
-package export
-
-import (
-	"fmt"
-	"log"
-)
-
-// Print solutions into a human friendly format for in the console.
-func (export *Export) PrintHumanReadableSolutions() {
-	for solutionIndex, solution := range export.Controller.Solutions {
-		log.Printf("\nSolution #%d:", solutionIndex+1)
-		fmt.Println("╔═══════════╗")
-		for rowIndex, row := range solution {
-			if rowIndex == 3 || rowIndex == 6 {
-				fmt.Println("╟───┼───┼───╢")
-			}
-			fmt.Println("║" + row[0:3] + "│" + row[3:6] + "│" + row[6:9] + "╢")
-		}
-		fmt.Println("╚═══════════╝")
-	}
-}

export/renderFlat.go

@@ -0,0 +1,15 @@
+package export
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// Render output as stored internally.
+func (export *Export) renderFlat() (render string) {
+	for solutionIndex, solution := range export.Controller.Solutions {
+		render += fmt.Sprintln("\nSolution #" + strconv.Itoa(solutionIndex+1) + ":")
+		render += fmt.Sprintln(solution)
+	}
+	return
+}

export/renderHumanReadable.go

@@ -0,0 +1,22 @@
+package export
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// Render solutions in a human friendly format.
+func (export *Export) renderHumanReadable() (render string) {
+	for solutionIndex, solution := range export.Controller.Solutions {
+		render += fmt.Sprintln("\nSolution #" + strconv.Itoa(solutionIndex+1) + ":")
+		render += fmt.Sprintln("╔═══════════╗")
+		for rowIndex, row := range solution {
+			if rowIndex == 3 || rowIndex == 6 {
+				render += fmt.Sprintln("╟───┼───┼───╢")
+			}
+			render += fmt.Sprintln("║" + row[0:3] + "│" + row[3:6] + "│" + row[6:9] + "╢")
+		}
+		render += fmt.Sprintln("╚═══════════╝")
+	}
+	return
+}

export/renderJSON.go

@@ -0,0 +1,35 @@
+package export
+
+import (
+	"encoding/json"
+)
+
+// Render JSON output.
+func (export *Export) renderJSON() (render string) {
+	type solution_type map[string]any
+	solutions := make([]solution_type, 0)
+
+	for solutionIndex, solution := range export.Controller.Solutions {
+		solutionMap := map[string]any{
+			"order": solutionIndex,
+			"row1":  solution[0],
+			"row2":  solution[1],
+			"row3":  solution[2],
+			"row4":  solution[3],
+			"row5":  solution[4],
+			"row6":  solution[5],
+			"row7":  solution[6],
+			"row8":  solution[7],
+			"row9":  solution[8],
+		}
+		solutions = append(solutions, solutionMap)
+	}
+	renderBytes, err := json.Marshal(solutions)
+	if err != nil {
+		export.Controller.Outputter.Println("ERROR: json.Marshal error:", err)
+		export.Controller.Outputter.Println("Printing solution as-is:", solutions)
+		return ""
+	}
+	render = string(renderBytes)
+	return
+}

flags/ParseFlags.go

@@ -2,7 +2,7 @@ package flags
 
 import (
 	"flag"
-	"log"
+	"fmt"
 	"os"
 	"runtime"
 	"strings"
@@ -24,14 +24,15 @@ func (flags *Flags) ParseFlags() {
 	flag.IntVar(&flags.Controller.NumCPUs, "numcpu", runtime.NumCPU(), "Number of CPU cores to assign to this task.")
 	flag.IntVar(&flags.Controller.Split, "split", 1, "Split the tasks in n parts. This depends on the availability of the first row.")
 	flag.IntVar(&flags.Controller.Part, "part", 1, "Process part x in n parts. Cannot be lower than 1, or higher than specified in split.")
-	flag.StringVar(&flags.Controller.Output, "output", "human", "Type of output. 'human' for human readable. 'flat' for flat as stored in memory output.")
+	flag.StringVar(&flags.Controller.Output, "output", "human", "Type of output. 'human' for human readable. 'flat' for flat as stored in memory output. 'json' for JSON output.")
+	flag.StringVar(&flags.Controller.Print, "print", "short", "'short': normal output;'long': normal output with timestamps; 'silent': Only print the results;")
 
 	// Parse the flags
 	flag.Parse()
 
 	// Process any changes to the CPU usage.
 	if flags.Controller.NumCPUs <= 0 {
-		log.Printf("ERROR: Number of CPU cores must be 1 or higher.\n\n")
+		fmt.Printf("ERROR: Number of CPU cores must be 1 or higher.\n\n")
 		flags.printUsage()
 		os.Exit(1)
 	}
@@ -42,7 +43,7 @@ func (flags *Flags) ParseFlags() {
 
 	// Process rows
 	if flags.Controller.Row1 == "000000000" || flags.Controller.Row2 == "000000000" || flags.Controller.Row3 == "000000000" || flags.Controller.Row4 == "000000000" || flags.Controller.Row5 == "000000000" || flags.Controller.Row6 == "000000000" || flags.Controller.Row7 == "000000000" || flags.Controller.Row8 == "000000000" || flags.Controller.Row9 == "000000000" {
-		log.Printf("ERROR: All parameters must be entered.\n\n")
+		fmt.Printf("ERROR: All parameters must be entered.\n\n")
 		flags.printUsage()
 		os.Exit(1)
 	}
@@ -61,22 +62,30 @@ func (flags *Flags) ParseFlags() {
 	// Process workload splitting
 	// Ensure split and part are 1 or higher
 	if flags.Controller.Split <= 0 || flags.Controller.Part <= 0 {
-		log.Printf("ERROR: '-split' and '-part' need to be 1 or higher.\n")
+		fmt.Printf("ERROR: '-split' and '-part' need to be 1 or higher.\n")
 		flags.printUsage()
 		os.Exit(1)
 	}
 
 	// Ensure part is between 1 and split
 	if flags.Controller.Part > flags.Controller.Split {
-		log.Printf("ERROR: '-part' cannot be bigger than `-split`.\n")
+		fmt.Printf("ERROR: '-part' cannot be bigger than `-split`.\n")
 		flags.printUsage()
 		os.Exit(1)
 	}
 
 	// Process output selection
 	flags.Controller.Output = strings.ToLower(flags.Controller.Output)
-	if flags.Controller.Output != "human" && flags.Controller.Output != "flat" {
-		log.Printf("ERROR: Invalid output, can only be 'human' or 'flat'.\n")
+	if flags.Controller.Output != "human" && flags.Controller.Output != "flat" && flags.Controller.Output != "json" {
+		fmt.Printf("ERROR: Invalid output, can only be 'human' or 'flat' or 'json'.\n")
+		flags.printUsage()
+		os.Exit(1)
+	}
+
+	// Process print selection
+	flags.Controller.Print = strings.ToLower(flags.Controller.Print)
+	if flags.Controller.Print != "short" && flags.Controller.Print != "long" && flags.Controller.Print != "silent" {
+		fmt.Printf("ERROR: Invalid Print, can only be 'short' or 'long' or 'silent'.\n")
 		flags.printUsage()
 		os.Exit(1)
 	}

flags/printUsage.go

@@ -6,19 +6,6 @@ import (
 	"os"
 )
 
-// Validate if the char provided is 0-9
-func (flags *Flags) validChar(char rune) (valid bool) {
-	decvals := [10]int{48, 49, 50, 51, 52, 53, 54, 55, 56, 57}
-
-	for _, value := range decvals {
-		if char == rune(value) {
-			valid = true
-		}
-	}
-
-	return
-}
-
 // Print help information for the end-user
 func (flags *Flags) printUsage() {
 	fmt.Fprintf(flag.CommandLine.Output(), "Usage of %s:\n", os.Args[0])

flags/validChar.go

@@ -0,0 +1,14 @@
+package flags
+
+// Validate if the char provided is 0-9
+func (flags *Flags) validChar(char rune) (valid bool) {
+	decvals := [10]int{48, 49, 50, 51, 52, 53, 54, 55, 56, 57}
+
+	for _, value := range decvals {
+		if char == rune(value) {
+			valid = true
+		}
+	}
+
+	return
+}

flags/validateRow.go

@@ -1,7 +1,7 @@
 package flags
 
 import (
-	"log"
+	"fmt"
 	"os"
 )
 
@@ -18,7 +18,7 @@ func (flags *Flags) validateRow(name string, row string) {
 
 	// 1. Make sure the row is 9 in length
 	if len(row) != 9 {
-		log.Printf("ERROR: Invalid length of %s (%s), must be 9 numbers\n\n", name, row)
+		fmt.Printf("ERROR: Invalid length of %s (%s), must be 9 numbers\n\n", name, row)
 		flags.printUsage()
 		os.Exit(1)
 	}
@@ -29,7 +29,7 @@ func (flags *Flags) validateRow(name string, row string) {
 	}
 
 	if !found {
-		log.Printf("ERROR: Invalid character of %s (%s), must be 9 numbers\n\n", name, row)
+		fmt.Printf("ERROR: Invalid character of %s (%s), must be 9 numbers\n\n", name, row)
 		flags.printUsage()
 		os.Exit(1)
 	}
@@ -46,7 +46,7 @@ func (flags *Flags) validateRow(name string, row string) {
 	}
 
 	if double {
-		log.Printf("ERROR: Double character of %s (%s), numbers between 1 and 9 may only be entered once\n\n", name, row)
+		fmt.Printf("ERROR: Double character of %s (%s), numbers between 1 and 9 may only be entered once\n\n", name, row)
 		flags.printUsage()
 		os.Exit(1)
 	}

main.go

@@ -1,29 +1,34 @@
 package main
 
 import (
-	"log"
+	"fmt"
 	"runtime"
 	"strconv"
 
 	"gitea.ligthert.net/golang/sudoku-funpark/controller"
 	"gitea.ligthert.net/golang/sudoku-funpark/export"
 	"gitea.ligthert.net/golang/sudoku-funpark/flags"
+	"gitea.ligthert.net/golang/sudoku-funpark/outputter"
 	"gitea.ligthert.net/golang/sudoku-funpark/solver"
 )
 
 func main() {
 	// Instantiate the interfaces
 	controller := controller.Controller{}
+	outp := outputter.Outputter{}
 	export := export.Export{Controller: &controller}
 	flags := flags.Flags{Controller: &controller}
-	solver := solver.Solver{Controller: &controller}
+	solver := solver.Solver{Controller: &controller, Outp: &outp}
 
 	// Parse and handle flags
 	flags.ParseFlags()
 
+	// Tell outp what kind of output is expected.
+	outp.OutputType = controller.Print
+
 	// Report number of CPUs being used, if set.
 	if runtime.NumCPU() != controller.NumCPUs {
-		log.Println("Using " + strconv.Itoa(controller.NumCPUs) + " CPUs, (was " + strconv.Itoa(runtime.NumCPU()) + ")")
+		outp.Println("Using " + strconv.Itoa(controller.NumCPUs) + " CPUs, (was " + strconv.Itoa(runtime.NumCPU()) + ")")
 	}
 
 	// Load blocks from CSV file
@@ -39,18 +44,12 @@ func main() {
 	}
 
 	// Print the total number of solutions to validate
-	log.Println("Number of (potential) solutions:", solver.Iter)
+	outp.Println("Number of (potential) solutions:", solver.Iter)
 
 	// Check the number of solutions
 	go solver.CheckCombinations()
 	solver.Tracker()
 
-	// Print the valid solutions
-	switch controller.Output {
-	case "human":
-		export.PrintHumanReadableSolutions()
-	case "flat":
-		export.PrintFlatSolutions()
-	}
+	fmt.Println(export.Export())
 
 }

outputter/Printf.go

@@ -0,0 +1,17 @@
+package outputter
+
+import (
+	"fmt"
+	"log"
+)
+
+func (outputter *Outputter) Printf(format string, args ...any) {
+	switch outputter.OutputType {
+	case "short":
+		fmt.Printf(format, args...)
+	case "long":
+		log.Printf(format, args...)
+	case "silent":
+		// Do nothing
+	}
+}

outputter/Println.go

@@ -0,0 +1,17 @@
+package outputter
+
+import (
+	"fmt"
+	"log"
+)
+
+func (outputter *Outputter) Println(msg ...any) {
+	switch outputter.OutputType {
+	case "short":
+		fmt.Println(msg...)
+	case "long":
+		log.Println(msg...)
+	case "silent":
+		// Do nothing
+	}
+}

outputter/types.go

@@ -0,0 +1,5 @@
+package outputter
+
+type Outputter struct {
+	OutputType string
+}

solver/LoadBlocks.go

@@ -2,7 +2,6 @@ package solver
 
 import (
 	"embed"
-	"log"
 	"strings"
 	"time"
 )
@@ -15,8 +14,8 @@ var f embed.FS
 // Load all possible blocks from CSV in to memory
 func (solver *Solver) LoadBlocks() {
 
-	defer solver.timeTrack(time.Now(), "Loaded blocks")
-	log.Println("Loading blocks")
+	defer solver.timeTrack(time.Now(), "Done!")
+	solver.Outp.Printf("Loading blocks... ")
 
 	var blocks []string
 

solver/PopulateBlocks.go

@@ -1,15 +1,14 @@
 package solver
 
 import (
-	"log"
 	"time"
 )
 
 // Find all possible blocks that can be used to find a solution.
 func (solver *Solver) PopulateBlocks() {
 
-	defer solver.timeTrack(time.Now(), "Populated blocks")
-	log.Println("Populating blocks")
+	defer solver.timeTrack(time.Now(), "Done!")
+	solver.Outp.Printf("Populating blocks... ")
 
 	solver.findBlocks(&solver.Controller.Row1, &solver.row1s)
 	solver.findBlocks(&solver.Controller.Row2, &solver.row2s)

solver/SelectWorkload.go

@@ -1,7 +1,6 @@
 package solver
 
 import (
-	"log"
 	"os"
 	"strconv"
 	"time"
@@ -12,12 +11,12 @@ import (
 // Modify solver.row1s so it limits the workload to what is only desired
 func (solver *Solver) SelectWorkload() {
 	if solver.Controller.Split > len(solver.row1s) {
-		log.Println("ERROR: Unable to divide the workload in " + strconv.Itoa(solver.Controller.Split) + " parts, when only " + strconv.Itoa(len(solver.row1s)) + " are available.\n\n")
+		solver.Outp.Println("ERROR: Unable to divide the workload in " + strconv.Itoa(solver.Controller.Split) + " parts, when only " + strconv.Itoa(len(solver.row1s)) + " are available.\n\n")
 		os.Exit(1)
 	}
 	defer solver.timeTrack(time.Now(), "Workload set")
-	log.Println("Setting workload")
-	log.Println("We are agent " + strconv.Itoa(solver.Controller.Part) + " of " + strconv.Itoa(solver.Controller.Split))
+	solver.Outp.Println("Setting workload")
+	solver.Outp.Println("We are agent " + strconv.Itoa(solver.Controller.Part) + " of " + strconv.Itoa(solver.Controller.Split))
 	workloads := solver.splitWorkload()
 	solver.setWorkload(workloads)
 }

solver/Tracker.go

@@ -1,7 +1,6 @@
 package solver
 
 import (
-	"log"
 	"strconv"
 	"time"
 )
@@ -12,7 +11,7 @@ func (solver *Solver) Tracker() {
 
 	// Add time tracking
 	defer solver.timeTrack(time.Now(), "Validated solutions")
-	log.Println("Validating solutions")
+	solver.Outp.Println("Validating solutions")
 
 	// Determine if the main-loop is done
 	var done bool
@@ -73,7 +72,7 @@ func (solver *Solver) Tracker() {
 			}
 
 			// Printing the progress
-			log.Println("Processing: " + strconv.Itoa(int(percentage)) + "% (" + strconv.FormatUint(solver.counter.Load(), 10) + "/" + strconv.Itoa(int(solver.Iter)) + "); Rate: " + strconv.FormatUint(rateDiff, 10) + "/sec for " + timer_elapsed.String() + "; Time left (est.): " + est_fin)
+			solver.Outp.Println("Processing: " + strconv.Itoa(int(percentage)) + "% (" + strconv.FormatUint(solver.counter.Load(), 10) + "/" + strconv.Itoa(int(solver.Iter)) + "); Rate: " + strconv.FormatUint(rateDiff, 10) + "/sec for " + timer_elapsed.String() + "; Time left (est.): " + est_fin)
 
 			// After we are done printing, exit this for-loop
 			if percentage == 100 {

solver/timeTrack.go

@@ -1,7 +1,6 @@
 package solver
 
 import (
-	"log"
 	"time"
 )
 
@@ -9,5 +8,5 @@ import (
 // Use with `defer`
 func (solver *Solver) timeTrack(start time.Time, msg string) {
 	elapsed := time.Since(start)
-	log.Printf("%s (%s)", msg, elapsed)
+	solver.Outp.Printf("%s (%s)\n", msg, elapsed)
 }

solver/types.go

@@ -4,6 +4,7 @@ import (
 	"sync/atomic"
 
 	"gitea.ligthert.net/golang/sudoku-funpark/controller"
+	"gitea.ligthert.net/golang/sudoku-funpark/outputter"
 )
 
 // Solve a given Sudoku puzzle by iterating through all possible solutions.
@@ -33,4 +34,6 @@ type Solver struct {
 	counter atomic.Uint64
 	// Slice of rates for accurate duration estimation.
 	rates []uint64
+	// Reference to Outputter interface
+	Outp *outputter.Outputter
 }