From: Ummon <greg.burri@gmail.com>
Date: Fri, 29 May 2015 19:44:35 +0000 (+0200)
Subject: First commit.
X-Git-Url: http://git.euphorik.ch/?p=sudokuSolver.git;a=commitdiff_plain;h=93c2731de053d0698800eb8a7ba1a475a38e58cc

First commit.
---

93c2731de053d0698800eb8a7ba1a475a38e58cc
diff --git a/SudokuSolver.sln b/SudokuSolver.sln
new file mode 100644
index 0000000..3e0c525
--- /dev/null
+++ b/SudokuSolver.sln
@@ -0,0 +1,17 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 2012
+Project("{f2a71f9b-5d33-465a-a702-920d77279786}") = "SudokuSolver", "SudokuSolver\SudokuSolver.fsproj", "{244C26E9-4AA3-42E2-BFD9-4CFB848C7230}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|x86 = Debug|x86
+		Release|x86 = Release|x86
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{244C26E9-4AA3-42E2-BFD9-4CFB848C7230}.Debug|x86.ActiveCfg = Debug|x86
+		{244C26E9-4AA3-42E2-BFD9-4CFB848C7230}.Debug|x86.Build.0 = Debug|x86
+		{244C26E9-4AA3-42E2-BFD9-4CFB848C7230}.Release|x86.ActiveCfg = Release|x86
+		{244C26E9-4AA3-42E2-BFD9-4CFB848C7230}.Release|x86.Build.0 = Release|x86
+	EndGlobalSection
+EndGlobal
diff --git a/SudokuSolver/AssemblyInfo.fs b/SudokuSolver/AssemblyInfo.fs
new file mode 100644
index 0000000..0ec66d0
--- /dev/null
+++ b/SudokuSolver/AssemblyInfo.fs
@@ -0,0 +1,21 @@
+module SudokuSolver.AssemblyInfo
+open System.Reflection
+open System.Runtime.CompilerServices
+
+[<assembly: AssemblyTitle("SudokuSolver")>]
+[<assembly: AssemblyDescription("")>]
+[<assembly: AssemblyConfiguration("")>]
+[<assembly: AssemblyCompany("")>]
+[<assembly: AssemblyProduct("")>]
+[<assembly: AssemblyCopyright("gburri")>]
+[<assembly: AssemblyTrademark("")>]
+
+// The assembly version has the format {Major}.{Minor}.{Build}.{Revision}
+
+[<assembly: AssemblyVersion("1.0.0.0")>]
+
+//[<assembly: AssemblyDelaySign(false)>]
+//[<assembly: AssemblyKeyFile("")>]
+
+()
+
diff --git a/SudokuSolver/Program.fs b/SudokuSolver/Program.fs
new file mode 100644
index 0000000..3402bc5
--- /dev/null
+++ b/SudokuSolver/Program.fs
@@ -0,0 +1,28 @@
+module SudokuSolver.Main
+
+module Solver = Version1
+
+open System
+open System.IO
+
+[<EntryPoint>]
+let main argv = 
+    use fs = new FileStream ("../../../sudokus/mm_22.txt", FileMode.Open, FileAccess.Read)
+    use sr = new StreamReader (fs)
+
+    while sr.Peek () <> -1 do
+        let b = Solver.Board sr
+        b.Show System.Console.Out
+
+        printfn "vvvvvvvvvvv"
+
+        let timer = System.Diagnostics.Stopwatch ()
+        timer.Start ()
+
+        if b.Solve () 
+        then b.Show System.Console.Out
+        else printfn "No solution"
+
+        timer.Stop ()
+        printfn "Time: %A ms" timer.ElapsedMilliseconds
+    0
\ No newline at end of file
diff --git a/SudokuSolver/SudokuSolver.fsproj b/SudokuSolver/SudokuSolver.fsproj
new file mode 100644
index 0000000..631f372
--- /dev/null
+++ b/SudokuSolver/SudokuSolver.fsproj
@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
+    <ProjectGuid>{244C26E9-4AA3-42E2-BFD9-4CFB848C7230}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <RootNamespace>SudokuSolver</RootNamespace>
+    <AssemblyName>SudokuSolver</AssemblyName>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug</OutputPath>
+    <DefineConstants>DEBUG</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <Externalconsole>true</Externalconsole>
+    <Tailcalls>false</Tailcalls>
+    <PlatformTarget>x86</PlatformTarget>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
+    <DebugSymbols>false</DebugSymbols>
+    <DebugType>none</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release</OutputPath>
+    <ErrorReport>prompt</ErrorReport>
+    <PlatformTarget>x86</PlatformTarget>
+    <Externalconsole>true</Externalconsole>
+    <Tailcalls>true</Tailcalls>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="mscorlib" />
+    <Reference Include="FSharp.Core" />
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Numerics" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="AssemblyInfo.fs" />
+    <Compile Include="Version1.fs" />
+    <Compile Include="Version2.fs" />
+    <Compile Include="Program.fs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\3.1\Framework\v4.0\Microsoft.FSharp.Targets" />
+</Project>
\ No newline at end of file
diff --git a/SudokuSolver/Version1.fs b/SudokuSolver/Version1.fs
new file mode 100644
index 0000000..f0216ad
--- /dev/null
+++ b/SudokuSolver/Version1.fs
@@ -0,0 +1,151 @@
+module SudokuSolver.Version1
+
+open System
+open System.IO
+open System.Collections.Generic
+
+let printUsage progname = 
+    printfn "Usage: %A <filename>" progname
+
+type Pos = 
+    { i: int; j: int }
+    member this.Next : Pos option = 
+        match this with
+        | { i = 8; j = 8 } -> None
+        | { i = i; j = 8 } -> Some { i = i + 1; j = 0 }
+        | { i = _; j = j } -> Some { this with j = j + 1 }
+
+let zoneRange c = 
+    match c with
+    | 0 | 1 | 2 -> [0 .. 2]
+    | 3 | 4 | 5 -> [3 .. 5]
+    | _ -> [6 .. 8]
+
+// All possible positions.
+let AllPos = seq {
+    for i in 0 .. 8 do
+       for j in 0 .. 8 -> { i = i; j = j } }
+
+type Board (values : seq<int>) =
+    let size = 9
+    let board = Array2D.create size size 0
+
+    do
+        Seq.take (size * size) values |> Seq.zip AllPos |> Seq.iter (fun ({ i = iVal; j = jVal}, value) -> 
+            board.[iVal, jVal] <- value)
+
+    let get pos = board.[pos.i, pos.j]
+    let set pos value = board.[pos.i, pos.j] <- value
+
+    let rec nextFree (pos : Pos) : Pos option =
+        match pos.Next with
+        | Some pos -> if get pos = 0 then Some pos else nextFree pos
+        | _ -> None
+
+    let isValid pos n =
+        List.forall (fun j -> get { pos with j = j } <> n) [0 .. 8] && 
+        List.forall (fun i -> get { pos with i = i } <> n) [0 .. 8] &&
+        List.forall (fun (i, j) -> get { i = i; j = j } <> n) [ 
+            for i' in zoneRange pos.i do
+                for j' in zoneRange pos.j -> i', j' ]
+
+    let validNumbers pos =
+        [
+            let valid = isValid pos
+            for n in 1 .. 9 do
+                if valid n then yield n ]
+
+    let show (output : TextWriter) =
+        for i in 0 .. size - 1 do
+            for j in 0 .. size - 1 do
+                if board.[i, j] = 0
+                then output.Write '.' 
+                else output.Write board.[i, j]
+                if (j + 1) % 3 = 0 && j <> size - 1 then
+                    output.Write '|'
+            output.WriteLine ()
+            if (i + 1) % 3 = 0 && i <> size - 1 then
+                output.WriteLine "-----------"         
+
+
+    let presolve () =
+        let (|OnlyOneNumber|_|) (pos : Pos) =
+            if get pos <> 0
+            then None
+            else
+                let numbers = Array.create 10 false
+                let nb = ref 0
+                let add n = 
+                    if not numbers.[n]
+                    then
+                        numbers.[n] <- true
+                        nb := !nb + 1
+
+                for i in 0 .. 8 do get { pos with i = i } |> add
+                for j in 0 .. 8 do get { pos with j = j } |> add
+                for i in zoneRange pos.i do
+                    for j in zoneRange pos.j do
+                        get { i = i; j = j } |> add
+
+                match !nb with
+                | 9 -> try Some (Array.findIndex not numbers) with _ -> None
+                | 10 -> None
+                | _ ->
+                    // For all remaining numbers.
+                    let remainingNumbers = Array.mapi (fun i p -> i, p) numbers 
+                                            |> Array.fold (fun acc (i, p) -> if not p then i :: acc else acc) []
+
+                    let rec findNumber numbers =
+                        match numbers with
+                        | [] -> None
+                        | n :: tail ->
+                            // If there is no other valid position, then the current is the only one.
+                            if seq {
+                                    for i in 0 .. 8 do
+                                        let pos' = { pos with i = i }
+                                        if i <> pos.i && get pos' = 0
+                                        then yield not (isValid pos' n) } |> Seq.forall id ||
+                               seq {
+                                    for j in 0 .. 8 do
+                                        let pos' = { pos with j = j }
+                                        if j <> pos.j && get pos' = 0
+                                        then yield not (isValid pos' n) } |> Seq.forall id ||
+                               seq {
+                                    for i in zoneRange pos.i do
+                                        for j in zoneRange pos.j do
+                                            let pos' = { i = i; j = j }
+                                            if pos' <> pos && get pos' = 0
+                                            then yield not (isValid pos' n) } |> Seq.forall id
+                            then Some n
+                            else findNumber tail
+
+                    findNumber remainingNumbers
+
+        while Seq.exists (fun pos -> 
+            match pos with
+            | OnlyOneNumber n -> set pos n; true
+            | _ -> false) AllPos do ()
+
+    new (input : TextReader) =
+        Board (seq {
+            while input.Peek () <> -1 do
+                match char (input.Read ()) with
+                | ' ' | '.' | '0' -> yield 0
+                | a when Char.IsDigit a -> yield int (Char.GetNumericValue a)
+                | _ -> () } |> Seq.take 81)
+
+    member this.Show = show
+    
+    member this.Solve () =
+        let rec solveFrom pos : bool = // Returns true if the solution is valid and complete.
+            match nextFree pos with
+            | Some pos' -> 
+                if List.exists (fun n -> set pos' n; solveFrom pos') (validNumbers pos')
+                then true
+                else 
+                    set pos' 0
+                    false
+            | _ -> true
+        presolve ()
+        solveFrom { i = 0; j = -1 }
+
diff --git a/SudokuSolver/Version2.fs b/SudokuSolver/Version2.fs
new file mode 100644
index 0000000..a05d072
--- /dev/null
+++ b/SudokuSolver/Version2.fs
@@ -0,0 +1,150 @@
+module SudokuSolver.Version2
+
+open System
+open System.IO
+open System.Collections.Generic
+
+let printUsage progname = 
+    printfn "Usage: %A <filename>" progname
+
+type Pos = 
+    { i: int; j: int }
+    member this.Next : Pos option = 
+        match this with
+        | { i = 8; j = 8 } -> None
+        | { i = i; j = 8 } -> Some { i = i + 1; j = 0 }
+        | { i = _; j = j } -> Some { this with j = j + 1 }
+
+let zoneRange c = 
+    match c with
+    | 0 | 1 | 2 -> [0 .. 2]
+    | 3 | 4 | 5 -> [3 .. 5]
+    | _ -> [6 .. 8]
+
+// All possible positions.
+let AllPos = seq {
+    for i in 0 .. 8 do
+       for j in 0 .. 8 -> { i = i; j = j } }
+
+type Board (values : seq<int>) =
+    let size = 9
+    let board = Array2D.create size size 0
+
+    do
+        Seq.take (size * size) values |> Seq.zip AllPos |> Seq.iter (fun ({ i = iVal; j = jVal}, value) -> 
+            board.[iVal, jVal] <- value)
+
+    let get pos = board.[pos.i, pos.j]
+    let set pos value = board.[pos.i, pos.j] <- value
+
+    let rec nextFree (pos : Pos) : Pos option =
+        match pos.Next with
+        | Some pos -> if get pos = 0 then Some pos else nextFree pos
+        | _ -> None
+
+    let isValid pos n =
+        List.forall (fun j -> get { pos with j = j } <> n) [0 .. 8] && 
+        List.forall (fun i -> get { pos with i = i } <> n) [0 .. 8] &&
+        List.forall (fun (i, j) -> get { i = i; j = j } <> n) [ 
+            for i' in zoneRange pos.i do
+                for j' in zoneRange pos.j -> i', j' ]
+
+    let validNumbers pos =
+        [
+            let valid = isValid pos
+            for n in 1 .. 9 do
+                if valid n then yield n ]
+
+    let show (output : TextWriter) =
+        for i in 0 .. size - 1 do
+            for j in 0 .. size - 1 do
+                if board.[i, j] = 0
+                then output.Write '.' 
+                else output.Write board.[i, j]
+                if (j + 1) % 3 = 0 && j <> size - 1 then
+                    output.Write '|'
+            output.WriteLine ()
+            if (i + 1) % 3 = 0 && i <> size - 1 then
+                output.WriteLine "-----------"         
+
+
+    let presolve () =
+        let (|OnlyOneNumber|_|) (pos : Pos) =
+            if get pos <> 0
+            then None
+            else
+                let numbers = Array.create 10 false
+                let nb = ref 0
+                let add n = 
+                    if not numbers.[n]
+                    then
+                        numbers.[n] <- true
+                        nb := !nb + 1
+
+                for i in 0 .. 8 do get { pos with i = i } |> add
+                for j in 0 .. 8 do get { pos with j = j } |> add
+                for i in zoneRange pos.i do
+                    for j in zoneRange pos.j do
+                        get { i = i; j = j } |> add
+
+                match !nb with
+                | 9 -> try Some (Array.findIndex not numbers) with _ -> None
+                | 10 -> None
+                | _ ->
+                    // For all remaining numbers.
+                    let remainingNumbers = Array.mapi (fun i p -> i, p) numbers 
+                                            |> Array.fold (fun acc (i, p) -> if not p then i :: acc else acc) []
+
+                    let rec findNumber numbers =
+                        match numbers with
+                        | [] -> None
+                        | n :: tail ->
+                            // If there is no other valid position, then the current is the only one.
+                            if seq {
+                                    for i in 0 .. 8 do
+                                        let pos' = { pos with i = i }
+                                        if i <> pos.i && get pos' = 0
+                                        then yield not (isValid pos' n) } |> Seq.forall id ||
+                               seq {
+                                    for j in 0 .. 8 do
+                                        let pos' = { pos with j = j }
+                                        if j <> pos.j && get pos' = 0
+                                        then yield not (isValid pos' n) } |> Seq.forall id ||
+                               seq {
+                                    for i in zoneRange pos.i do
+                                        for j in zoneRange pos.j do
+                                            let pos' = { i = i; j = j }
+                                            if pos' <> pos && get pos' = 0
+                                            then yield not (isValid pos' n) } |> Seq.forall id
+                            then Some n
+                            else findNumber tail
+
+                    findNumber remainingNumbers
+
+        while Seq.exists (fun pos -> 
+            match pos with
+            | OnlyOneNumber n -> set pos n; true
+            | _ -> false) AllPos do ()
+
+    new (input : TextReader) =
+        Board (seq {
+            while input.Peek () <> -1 do
+                match char (input.Read ()) with
+                | ' ' | '.' | '0' -> yield 0
+                | a when Char.IsDigit a -> yield int (Char.GetNumericValue a)
+                | _ -> () } |> Seq.take 81)
+
+    member this.Show = show
+    
+    member this.Solve () =
+        let rec solveFrom pos : bool = // Returns true if the solution is valid and complete.
+            match nextFree pos with
+            | Some pos' -> 
+                if List.exists (fun n -> set pos' n; solveFrom pos') (validNumbers pos')
+                then true
+                else 
+                    set pos' 0
+                    false
+            | _ -> true
+        presolve ()
+        solveFrom { i = 0; j = -1 }
diff --git a/sudokus/mm_01.txt b/sudokus/mm_01.txt
new file mode 100644
index 0000000..0106ef1
--- /dev/null
+++ b/sudokus/mm_01.txt
@@ -0,0 +1,12 @@
+8.2|...|9.7
+.7.|...|.1.
+6..|1.7|..5
+-----------
+..1|.7.|4..
+...|8.6|...
+..4|.3.|6..
+-----------
+3..|9.8|..6
+.2.|...|.9.
+5.6|...|8.1
+
diff --git a/sudokus/mm_110.txt b/sudokus/mm_110.txt
new file mode 100644
index 0000000..7ac8f6f
--- /dev/null
+++ b/sudokus/mm_110.txt
@@ -0,0 +1,11 @@
+3 4|   |1 6
+ 8 |1 5| 4 
+5  |   |  2
+-----------
+ 6 |   | 1 
+   |417|   
+ 4 |   | 9 
+-----------
+1  |   |  8
+ 3 |7 2| 6 
+8 9|   |2 5
\ No newline at end of file
diff --git a/sudokus/mm_22.txt b/sudokus/mm_22.txt
new file mode 100644
index 0000000..cad55cf
--- /dev/null
+++ b/sudokus/mm_22.txt
@@ -0,0 +1,11 @@
+3 5| 68|   
+81 | 74|   
+ 69|   | 4 
+-----------
+ 2 | 9 |   
+ 5 | 2 | 3 
+   | 8 | 7 
+-----------
+ 7 |   |16 
+   |64 | 59
+   |31 |4 8
\ No newline at end of file
diff --git a/sudokus/mm_47.txt b/sudokus/mm_47.txt
new file mode 100644
index 0000000..2600216
--- /dev/null
+++ b/sudokus/mm_47.txt
@@ -0,0 +1,12 @@
+...|6.9|...
+..3|...|9..
+.5.|874|.3.
+-----------
+6.1|...|8.7
+...|.1.|...
+3.7|...|6.9
+-----------
+.7.|185|.4.
+..5|...|1..
+...|2.7|...
+
diff --git a/sudokus/mm_52.txt b/sudokus/mm_52.txt
new file mode 100644
index 0000000..ff84d93
--- /dev/null
+++ b/sudokus/mm_52.txt
@@ -0,0 +1,11 @@
+   |   |   
+  4|3 9|2  
+ 81| 5 |49 
+-----------
+ 5 |9 2| 7 
+  6| 7 |1  
+ 2 |8 6| 5 
+-----------
+ 67| 9 |83 
+  5|2 4|6  
+   |   |   
\ No newline at end of file
diff --git a/sudokus/naked_single.txt b/sudokus/naked_single.txt
new file mode 100644
index 0000000..66160df
--- /dev/null
+++ b/sudokus/naked_single.txt
@@ -0,0 +1,11 @@
+...|...|...
+...|...|...
+...|.4.|...
+-----------
+...|6..|...
+...|..9|...
+2.8|...|..3
+-----------
+...|.1.|...
+...|.5.|...
+...|...|...
diff --git a/sudokus/sudoku_easy.txt b/sudokus/sudoku_easy.txt
new file mode 100644
index 0000000..6b4460a
--- /dev/null
+++ b/sudokus/sudoku_easy.txt
@@ -0,0 +1,11 @@
+ 3 |  6| 72
+  2| 8 |91 
+ 6 |   |48 
+-----------
+   |4  |  7
+7  |2 1|  9
+2  |  7|   
+-----------
+ 17|   | 2 
+ 58| 7 |3  
+92 |6  | 5 
\ No newline at end of file
diff --git a/sudokus/sudoku_empty.txt b/sudokus/sudoku_empty.txt
new file mode 100644
index 0000000..eaf3324
--- /dev/null
+++ b/sudokus/sudoku_empty.txt
@@ -0,0 +1,11 @@
+   |   |   
+   |   |   
+   |   |   
+-----------
+   |   |   
+   |   |   
+   |   |   
+-----------
+   |   |   
+   |   |   
+   |   |   
\ No newline at end of file
diff --git a/sudokus/sudoku_hard.txt b/sudokus/sudoku_hard.txt
new file mode 100644
index 0000000..341eca4
--- /dev/null
+++ b/sudokus/sudoku_hard.txt
@@ -0,0 +1,11 @@
+ 79|   |8  
+3  |  5| 6 
+5  |4  |2 3
+-----------
+   | 5 |   
+ 4 |2 6| 7 
+   | 9 |   
+-----------
+4 7|  1|  5
+ 3 |5  |  7
+  8|   |62 
\ No newline at end of file
diff --git a/sudokus/sudoku_hard_2.txt b/sudokus/sudoku_hard_2.txt
new file mode 100644
index 0000000..dd0b2fc
--- /dev/null
+++ b/sudokus/sudoku_hard_2.txt
@@ -0,0 +1,11 @@
+8..|...|...
+..3|6..|...
+.7.|.9.|2..
+-----------
+.5.|..7|...
+...|.45|7..
+...|1..|.3.
+-----------
+..1|...|.68
+..8|5..|.1.
+.9.|...|4..
\ No newline at end of file
diff --git a/sudokus/sudoku_impossible.txt b/sudokus/sudoku_impossible.txt
new file mode 100644
index 0000000..488519f
--- /dev/null
+++ b/sudokus/sudoku_impossible.txt
@@ -0,0 +1,11 @@
+11 |   |   
+   |   |   
+   |   |   
+-----------
+   |   |   
+   |   |   
+   |   |   
+-----------
+   |   |   
+   |   |   
+   |   |   
\ No newline at end of file
diff --git a/sudokus/sudoku_slow.txt b/sudokus/sudoku_slow.txt
new file mode 100644
index 0000000..62eae32
--- /dev/null
+++ b/sudokus/sudoku_slow.txt
@@ -0,0 +1 @@
+4...3.......6..8..........1....5..9..8....6...7.2........1.27..5.3....4.9........
\ No newline at end of file
diff --git a/sudokus/sudokus.txt b/sudokus/sudokus.txt
new file mode 100644
index 0000000..e299c76
--- /dev/null
+++ b/sudokus/sudokus.txt
@@ -0,0 +1,20 @@
+..............3.85..1.2.......5.7.....4...1...9.......5......73..2.1........4...9
+.......12........3..23..4....18....5.6..7.8.......9.....85.....9...4.5..47...6...
+.2..5.7..4..1....68....3...2....8..3.4..2.5.....6...1...2.9.....9......57.4...9..
+........3..1..56...9..4..7......9.5.7.......8.5.4.2....8..2..9...35..1..6........
+12.3....435....1....4........54..2..6...7.........8.9...31..5.......9.7.....6...8
+1.......2.9.4...5...6...7...5.9.3.......7.......85..4.7.....6...3...9.8...2.....1
+.......39.....1..5..3.5.8....8.9...6.7...2...1..4.......9.8..5..2....6..4..7.....
+12.3.....4.....3....3.5......42..5......8...9.6...5.7...15..2......9..6......7..8
+..3..6.8....1..2......7...4..9..8.6..3..4...1.7.2.....3....5.....5...6..98.....5.
+1.......9..67...2..8....4......75.3...5..2....6.3......9....8..6...4...1..25...6.
+..9...4...7.3...2.8...6...71..8....6....1..7.....56...3....5..1.4.....9...2...7..
+....9..5..1.....3...23..7....45...7.8.....2.......64...9..1.....8..6......54....7
+4...3.......6..8..........1....5..9..8....6...7.2........1.27..5.3....4.9........
+7.8...3.....2.1...5.........4.....263...8.......1...9..9.6....4....7.5...........
+3.7.4...........918........4.....7.....16.......25..........38..9....5...2.6.....
+........8..3...4...9..2..6.....79.......612...6.5.2.7...8...5...1.....2.4.5.....3
+.......1.4.........2...........5.4.7..8...3....1.9....3..4..2...5.1........8.6...
+.......12....35......6...7.7.....3.....4..8..1...........12.....8.....4..5....6..
+1.......2.9.4...5...6...7...5.3.4.......6........58.4...2...6...3...9.8.7.......1
+.....1.2.3...4.5.....6....7..2.....1.8..9..3.4.....8..5....2....9..3.4....67.....
diff --git a/sudokus/unique_candidate.txt b/sudokus/unique_candidate.txt
new file mode 100644
index 0000000..2c4e1ed
--- /dev/null
+++ b/sudokus/unique_candidate.txt
@@ -0,0 +1,11 @@
+...|...|...
+...|...|...
+...|...|...
+-----------
+4..|...|...
+...|3.2|...
+...|...|..4
+-----------
+...|...|...
+...|...|...
+...|...|...