Add Valid Sudoku

ValidSudoku/ValidSudoku.Tests/ValidSudoku.Tests.csproj

@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
+    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector" Version="3.1.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\ValidSudoku\ValidSudoku.csproj" />
+  </ItemGroup>
+
+</Project>

ValidSudoku/ValidSudoku.Tests/ValidSudokuTests.cs

@@ -0,0 +1,55 @@
+using Xunit;
+
+namespace ValidSudoku.Tests
+{
+    public class ValidSudokuTests
+    {
+        [Fact]
+        public void Test_When_The_Input_Is_A_Valid_Sudoku_Board_Then_Return_True()
+        {
+            // arrange 
+            var input = new char[][]
+            {
+                new char[] {'5','3','.','.','7','.','.','.','.'},
+                new char[] {'6','.','.','1','9','5','.','.','.'},
+                new char[] {'.','9','8','.','.','.','.','6','.'},
+                new char[] {'8','.','.','.','6','.','.','.','3'},
+                new char[] {'4','.','.','8','.','3','.','.','1'},
+                new char[] {'7','.','.','.','2','.','.','.','6'},
+                new char[] {'.','6','.','.','.','.','2','8','.'},
+                new char[] {'.','.','.','4','1','9','.','.','5'},
+                new char[] {'.','.','.','.','8','.','.','7','9'}
+            };
+
+            // act
+            var actual = ValidSudoku.IsValid(input);
+
+            // assert
+            Assert.True(actual);
+        }
+
+        [Fact]
+        public void Test_When_The_Input_Is_An_Invalid_Sudoku_Board_Then_Return_False()
+        {
+            // arrange 
+            var input = new char[][]
+            {
+                new char[] {'8','3','.','.','7','.','.','.','.'},
+                new char[] {'6','.','.','1','9','5','.','.','.'},
+                new char[] {'.','9','8','.','.','.','.','6','.'},
+                new char[] {'8','.','.','.','6','.','.','.','3'},
+                new char[] {'4','.','.','8','.','3','.','.','1'},
+                new char[] {'7','.','.','.','2','.','.','.','6'},
+                new char[] {'.','6','.','.','.','.','2','8','.'},
+                new char[] {'.','.','.','4','1','9','.','.','5'},
+                new char[] {'.','.','.','.','8','.','.','7','9'},
+            };
+
+            // act
+            var actual = ValidSudoku.IsValid(input);
+
+            // assert
+            Assert.False(actual);
+        }
+    }
+}

ValidSudoku/ValidSudoku.sln

@@ -0,0 +1,31 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.0.31919.166
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ValidSudoku", "ValidSudoku\ValidSudoku.csproj", "{50414EC2-E8BA-464C-AD2A-7AA0B80FD740}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ValidSudoku.Tests", "ValidSudoku.Tests\ValidSudoku.Tests.csproj", "{55735F2A-492F-4D46-8768-81867047B172}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{50414EC2-E8BA-464C-AD2A-7AA0B80FD740}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{50414EC2-E8BA-464C-AD2A-7AA0B80FD740}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{50414EC2-E8BA-464C-AD2A-7AA0B80FD740}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{50414EC2-E8BA-464C-AD2A-7AA0B80FD740}.Release|Any CPU.Build.0 = Release|Any CPU
+		{55735F2A-492F-4D46-8768-81867047B172}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{55735F2A-492F-4D46-8768-81867047B172}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{55735F2A-492F-4D46-8768-81867047B172}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{55735F2A-492F-4D46-8768-81867047B172}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {7FA59BB6-0BD0-4B38-AF2A-81F2F7BDE196}
+	EndGlobalSection
+EndGlobal

ValidSudoku/ValidSudoku/ValidSudoku.cs

@@ -0,0 +1,40 @@
+namespace ValidSudoku
+{
+    //Determine if a 9 x 9 Sudoku board is valid.Only the filled cells need to be validated according to the following rules:
+
+    //Each row must contain the digits 1-9 without repetition.
+    //Each column must contain the digits 1-9 without repetition.
+    //Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition.
+    //Note:
+
+    //A Sudoku board (partially filled) could be valid but is not necessarily solvable.
+    //Only the filled cells need to be validated according to the mentioned rules.
+    public class ValidSudoku
+    {
+        public static bool IsValid(char[][] board)
+        {
+            HashSet<string> seen = new HashSet<string>();
+
+            for (int i = 0; i < 9; i++)
+            {
+                for (int j = 0; j < 9; j++)
+                {
+                    char current = board[i][j];
+                    if (current != '.')
+                    {
+                        if (
+                            !seen.Add(current + " row " + i) ||
+                            !seen.Add(current + " column " + j) ||
+                            !seen.Add(current + " subbox " + i/3 + "-" + j/3)
+                        )
+                        {
+                            return false;
+                        }
+                    }
+
+                }
+            }
+            return true;
+        }
+    }
+}

ValidSudoku/ValidSudoku/ValidSudoku.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>